JP2013144528A - Precure tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precure tread that can prevent cushion rubber from flowing into a back face groove formed on a back surface of the precure tread, and in which wear of a retread tire allows the back surface groove to reliably fulfill a function as a groove when the back surface groove is exposed to a tread.SOLUTION: The precure tread 1 includes a contact area 3 positioned on a tire tread side and a back surface 21 positioned on a base tire side, and also includes a surface groove and the back surface groove 23 on the contact area 3 and the back surface 21, respectively, where the precure tread is bonded to a crown of the base tire. A communication groove 25 connecting at least the back surface grooves 23 adjacent each other is provided on the back surface 21, and a through-hole 27 communicating with the communication groove 25 is provided on the contact area 3.

Description

  The present invention relates to a precure tread for retreaded tires, and in particular, it has a back groove that is exposed as the ground contact surface wears on the back surface, and even if the tread reaches the end of wear, it exhibits sufficient ice and snow performance etc. It relates to what is to be secured.

  Pneumatic tires are often able to withstand sufficient use even after the end of their tread rubber life, and after removing the remaining tread of worn tires by buffing to form a base tire, a cushion is placed on the crown of the base tire. A vulcanized precured tread is vulcanized and integrated through rubber and can be used again as a retread tire.

  By the way, it is desirable that the retreaded tire is capable of sufficiently exhibiting the snow and snow performance even when the tread reaches the end of wear, and as a conventional technique in this regard, there is a back surface of the precure tread located on the base tire side. It has been proposed to effectively prevent a decrease in ice / snow performance or the like by forming a back surface groove exposed on the tread surface with wear in the part (see, for example, Patent Document 1).

JP-A-3-153406

  By the way, as shown in FIG. 5, the integration of the precure tread into the base tire is performed by placing the precure tread 100 on the crown portion of the base tire via the cushion rubber 31, and then the base with the precure tread. By wrapping the tire with a vulcanization envelope and loading it into a vulcanization can at a predetermined temperature and pressure, the precure tread 100 is brought into close contact with the base tire 29 by the vulcanization envelope, and the cushion rubber 31 is vulcanized in this state. Is done. For this reason, as a result of the cushion rubber 31 crushed between the precure tread 100 and the base tire 29 during vulcanization flowing into the back groove 23 formed in the back surface portion of the precure tread 100, the back groove 23 is cushioned. When the back surface groove 23 closed by the rubber 31 is exposed to the tread surface due to wear of the ground contact surface portion, there is a problem that the function as the groove cannot be sufficiently performed.

  Therefore, the present invention suppresses the inflow of the cushion rubber to the back groove formed on the back surface portion of the precure tread, and the groove is formed in the back groove when the back groove is exposed to the tread surface due to wear of the retread tire. The purpose is to propose a pre-cured tread that can reliably exhibit its functions.

  The present invention has been made to solve the above problems, and the precure tread of the present invention has a grounding surface portion located on the tire tread surface side and a back surface portion located on the base tire side, and the grounding In the pre-cured tread having a surface groove on the surface portion and a back surface groove on the back surface portion and bonded to the crown portion of the base tire, a communication groove that connects at least the adjacent back surface grooves is provided on the back surface portion, A through-hole communicating with the communication groove is provided in the ground surface portion.

  In the precure tread of this invention, it is preferable that the communication groove has a groove depth shallower than that of the back groove.

  Moreover, in the precure tread of this invention, it is preferable that the said through-hole is formed in the groove bottom of the said surface groove | channel.

Furthermore, in the precure tread of the present invention, the communication groove extends in the longitudinal direction of the precure tread and communicates between the back surface grooves adjacent to the longitudinal direction, and an inclination direction with respect to the longitudinal direction. And a communication lateral groove that communicates between the communication longitudinal grooves adjacent to each other in the inclined direction,
It is preferable that the through hole is formed so as to communicate with the communication lateral groove.

  Furthermore, in the precure tread of this invention, the surface groove includes a surface transverse groove extending in a direction inclined with respect to the longitudinal direction of the precure tread, and the communication transverse groove is formed at a position corresponding to the surface transverse groove. It is preferable that

  Moreover, in the precure tread of the present invention, the surface groove preferably includes a surface longitudinal groove extending in the longitudinal direction of the precure tread, and the through hole is provided at the groove bottom of the surface longitudinal groove. .

  Moreover, in the precure tread of this invention, it is preferable that the said back surface groove | channel is a sipe.

  In the precure tread of this invention, the precure tread is affixed to a base tire via an unvulcanized cushion rubber, covered with a vulcanization envelope, and pressurized between the vulcanization envelope and the outer surface of the tire. When vulcanizing in a vulcanizing can while supplying gas, the pressurized gas supplied between the vulcanization envelope and the outer surface of the tire is introduced into the back groove through the through hole and the communication groove. The inside of the back groove is pressurized, and the cushion rubber is prevented from flowing into the back groove.

  Therefore, according to the precure tread of the present invention, it is possible to suppress the cushion rubber from entering the back groove when being attached to the base tire, so that the back groove becomes a tread surface as the retread tire wears. When exposed, the back groove can reliably function as a groove.

It is a top view which shows a part of grounding-surface part of the precure tread of one Embodiment of this invention. It is a top view which shows a part of back part of the precure tread of FIG. It is sectional drawing which shows a mode when the precure tread of FIG. 1 is arrange | positioned in the crown part of a base tire via cushion rubber, and a vulcanization envelope is covered and vulcanized within a vulcanization can. When the precure tread of FIG. 1 is affixed to the crown portion of the base tire via a cushion rubber and vulcanized in a vulcanizing can while supplying pressurized gas between the vulcanization envelope and the outer surface of the tire It is a fragmentary sectional view of the tire which shows the mode. When a conventional precure tread is affixed to the crown of a base tire via a cushion rubber and vulcanized in a vulcanizing can while supplying pressurized gas between the vulcanization envelope and the outer surface of the tire It is a fragmentary sectional view of the tire which shows a mode.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a part of a contact surface part of a precure tread applied to a retread tire, and FIG. 2 is a plan view showing a part of a back part of the precure tread. In this specification, the longitudinal direction of the precure tread coincides with the tire circumferential direction of the retread tire, and the direction orthogonal to the longitudinal direction of the precure tread coincides with the tire width direction of the retread tire.

  The precure tread is vulcanized and integrated with a crown portion of a base tire formed by removing a tread of a used tire by buffing through a sheet-like cushion rubber.

  Here, as shown in FIG. 1, the precure tread 1 has four surface longitudinally extending in a zigzag shape in the longitudinal direction (vertical direction in FIG. 1) of the precure tread 1 on the ground contact surface portion 3 located on the tread side. It has grooves 5a, 5b, 5c, 5d. So-called sacrificial land portions 6a and 6b having a height lower than that of the tread surface are provided in the surface longitudinal grooves 5c and 5d located on the outer side in the tire width direction. Further, the central land portion 7 defined by the two surface longitudinal grooves 5a and 5b located on the center side includes a surface inclined groove 9 extending from one surface longitudinal groove 5a and terminating in the land portion 7 and the other surface longitudinal groove 5a. Surface inclined grooves 9 extending from the surface longitudinal grooves 5b and terminating in the land portion 7 are alternately arranged in the tire circumferential direction. Further, the surface inclined grooves 9 adjacent to each other in the longitudinal direction of the precure tread 1 are connected by a surface connecting groove 11.

  Further, the surface longitudinal grooves 5a and 5b located on the center side and the outer side in the tire width direction than the surface longitudinal grooves 5a and 5b (between the surface longitudinal grooves 5a and 5b and the widthwise edge of the precure tread in FIG. 1). The intermediate land portions 13a, 13b formed by the surface longitudinal grooves 5c, 5d positioned at the side and the side land portions 15a, 15b positioned outside the intermediate land portions 13a, 13b in the tire width direction are respectively pre-cured treads. It is divided into a plurality of blocks by surface lateral grooves 17 and 19 extending in a direction inclined with respect to one longitudinal direction. These surface vertical grooves 5a, 5b, 5c, 5d, surface inclined grooves 9, surface connecting grooves 11, and surface lateral grooves 17, 19 correspond to the surface grooves of the present invention. In addition, the tread pattern formed in the ground plane part 3 is not limited to the example of illustration.

  On the other hand, as shown in FIG. 2, the rear land portion 21 of the precure tread 1 located on the base tire side (the surface side bonded to the base tire) has a central land portion 7 and an intermediate land portion 13 a of the ground contact surface portion 3. , 13b and side land portions 15a, 15b are formed with a plurality of back grooves 23 extending in a zigzag shape along the tire width direction. In this embodiment, the back groove 23 is a sipe-like one that closes at least the opening end of the groove at the time of grounding when exposed to the tread tread with the wear of the ground surface portion 3 (for example, a groove width of about 1 mm). However, of course, the back surface groove 23 may not be closed at the time of grounding. The term “at the time of ground contact” as used herein refers to an industrial standard that is valid for the area where tires are produced and used, in Japan, JEARMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization). ) STANDARD MANUAL of the United States, in the United States TRA (THE TIRE and RIM ASSOCATION INC.) YEAR BOOK of YEAR BOOK, the air pressure (maximum air pressure) corresponding to the maximum load capacity is filled in the tire. It means a state where it is pressed against a flat surface with a load of 80% of the maximum load capacity.

  Here, the feature of the precure tread 1 is that the back surface portion 21 includes a communication groove 25 that connects at least the adjacent back surface grooves 23, and penetrates from the ground surface portion 3 to the back surface portion 21. 25 is provided with a through-hole 27 communicating with 25.

  In this embodiment, the communication groove 25 is set to have a groove depth shallower than the back surface groove 23 and narrower than the surface groove. The communication groove 25 extends in the longitudinal direction of the precure tread 1 and extends in a direction inclined to the longitudinal direction and a communication vertical groove 25a communicating between the back surface grooves 23 adjacent to the longitudinal direction, and is adjacent to the inclination direction. The communication vertical grooves 25a and 25a communicate with each other, and the through holes 27 are formed so as to communicate (open) with the communication horizontal grooves. The communication lateral groove is formed at a position substantially corresponding to the surface lateral groove. The communication groove 25 preferably has a groove width of 1 to 2 mm, and preferably has a groove depth of 0.5 to 1 mm. Here, the groove width and the groove depth of the communication groove 25 are values measured on a flat plate before the precure tread 1 is attached to the base tire.

Moreover, the through-hole is formed in the groove bottom of the surface vertical groove. In the illustrated example, the opening shape of the through hole is circular, but is not limited thereto, and may be rectangular, polygonal, elliptical, or the like. The maximum width (maximum diameter) of the through hole is preferably 3 mm, and the maximum opening area is preferably 9 mm ² .

  In order to integrate the precured tread 1 having such a configuration with the base tire 29, as shown in FIG. 3, first, an unvulcanized cushion rubber 31 is attached to the crown portion 29a of the base tire 29, and the pre-cured tread 1 is preliminarily bonded thereto. Place cure tread 1. Next, an annular vulcanization envelope 33 is put on the precure tread 1, and the end 33 a of the vulcanization envelope 33 is disposed between the bead portion 29 a of the base tire 29 with the precure tread 1 and the holding rim R. To do. Then, the base tire 29 with the precure tread 1 wrapped in the vulcanization envelope 33 is loaded into a vulcanization can (not shown) having a predetermined pressure and temperature, and the vulcanization envelope 33 is passed through the gas supply port 33 b of the vulcanization envelope 33. A gas g having a pressure (for example, about 500 kPa) lower than the pressure of the vulcanization can (for example, about 500 kPa) is supplied between the inner surface of the tire and the outer surface of the base tire 29 with the precure tread 1 to provide a differential pressure (for example, About 100 kPa) is generated, and the precure tread 1 is pressed against the base tire 29 with this differential pressure.

  At this time, as schematically shown in FIG. 4, the pressurized gas g supplied between the vulcanization envelope 33 and the outer surface of the base tire 29 with the precure tread 1 through the gas supply port 33 b Then, it is introduced into the back surface groove 23 through the communication groove 25, pressurizes the inside of the back surface groove 23, and suppresses the cushion rubber 31 from flowing into the back surface groove 23. In addition, since the pressure of the pressurized gas g is lower than the pressure of the vulcanizing can, the precure tread 1 is not peeled off from the base tire 29 by the supply of the pressurized gas g.

Therefore, according to the precure tread 1, the cushion rubber 31 can be prevented from entering the back surface groove 23 when being attached to the base tire 29, so that the back surface groove 23 is formed along with wear of the retread tire. When exposed on the tread surface, the back groove 23 can reliably function as a groove.
Such an effect of suppressing the inflow of the cushion rubber is particularly prominent when the rear groove 23 is a sipe that is easily closed by the inflow of the cushion rubber.

  Moreover, according to the precure tread 1 of this embodiment, since the groove depth of the communication groove 25 is set shallower than the back surface groove 23, the rigidity of the tread portion is still ensured even if the communication groove 25 is formed. be able to.

  Furthermore, according to the precure tread 1 of this embodiment, since the through hole 27 is formed in the groove bottom of the surface groove (surface longitudinal grooves 5c, 5d), the base tire with the vulcanization envelope 33 and the precure tread 1 When the pressurized gas g is supplied between the outer surface 29 and the outer surface 29, the through-hole 27 can be prevented from being blocked by the vulcanization envelope 33, and the through-groove 27 is formed in the land portion. The rigidity of the land part can be ensured.

  Furthermore, according to the precure tread 1 of this embodiment, the communication groove 25 extends in the longitudinal direction of the precure tread 1, and the communication longitudinal groove 25a communicates between the back surface grooves 23 adjacent to the longitudinal direction. And a communication lateral groove 25b that communicates between the communication longitudinal grooves 25a, 25a adjacent to each other in the inclination direction, and the through hole 27 is formed so as to communicate (open) with the communication lateral groove. The pressurized gas g between the sulfur envelope 33 and the outer surface of the base tire 29 with the precure tread 1 can be evenly supplied to the respective rear grooves 23, and the through holes 27 are respectively formed in the respective communication longitudinal grooves. Since it is not necessary to provide (because the number of the through holes 27 can be reduced), it is possible to mitigate a decrease in rigidity of the tread portion caused by the through holes 27.

  In addition, in this embodiment, the ground surface portion 3 is provided with the surface longitudinal grooves 5a to 5d extending in the longitudinal direction of the precure tread 1, and the through hole 27 is provided at the bottom of the surface longitudinal grooves 5c and 5d. The through-hole 27 can be prevented from being blocked by the vulcanization envelope 33, and compared with the case where the through-hole is provided at the bottom of the surface vertical grooves 5a and 5b located on the center side, The difference in distance to each back surface groove 23 can be made uniform, and the pressure loss when the pressurized gas g is supplied to the back surface groove 23 can be minimized.

  Next, a retread tire manufactured by attaching a precure tread according to the present invention to a base tire (a tire of Example 1), and a retread tire manufactured by attaching a conventional precure tread to a base tire (conventional example) No. 1 tire) and a snow and snow performance test on the back groove were conducted, which will be described. In addition, all the tires made as prototypes have a tire size of 295 / 75R22.5.

  The tire of Example 1 has a tread pattern shown in FIG. 1 on the contact surface portion, and a precure tread having a back groove (sipe having a width of 1 mm) and a communication groove shown in FIG. After being attached to the base tire, the base tire with precure tread was wrapped in a vulcanization envelope and loaded into a vulcanizing can according to a known vulcanization method, and vulcanized at a predetermined temperature and pressure. Is.

  The tire of Conventional Example 1 was manufactured by the same method as described above, using a precure tread having the same configuration as the precure tread in the tire of Example 1 except that it did not have through holes and communication grooves. Is.

  In the snow and snow performance test, the ground contact surface of each test tire was worn until the rear groove was exposed to the tread surface, and assembled to the applicable rim, with an internal pressure of 7.0 kPa (relative pressure) and a vehicle equipped with an anti-lock brake system. This was done by measuring the braking distance when the icy and snowy road surface was fully braked from 80 km / h under the riding load of one driver. The results are shown in Table 1. The results in Table 1 show the braking performance when the tire of the conventional example 1 is used as 100 and the braking performance when the tire of the example 1 is used as an index. The larger the value, the braking distance. Is short and indicates good snow and snow performance.

  As can be seen from the results in Table 1, according to the retread tire manufactured using the precure tread to which the present invention is applied, when the rear groove is exposed on the tread surface due to wear of the retread tire, the rear groove is formed as a groove. It is possible to exert the functions of

  According to the precure tread of the present invention, it is possible to suppress the cushion rubber from entering the back groove when being attached to the base tire, so that the back groove is exposed to the tread tread as the retread tire wears. In this case, the back groove can reliably function as a groove.

DESCRIPTION OF SYMBOLS 1 Precured tread 3 Grounding surface part 5a, 5b, 5c, 5d Surface vertical groove 7 Central land part 9 Surface inclined groove 13a, 13b Intermediate land part 15a, 15b Side land part 17, 19 Surface lateral groove 21 Back surface part 23 Back surface groove 25 Communication groove 25a Communication vertical groove 25b Communication lateral groove 27 Through hole 29 Tire 31 Cushion rubber 33 Vulcanization envelope

Claims (7)

It has a grounding surface portion located on the tire tread side and a back surface portion located on the base tire side, and has a surface groove on the grounding surface portion and a back surface groove on the back surface portion, and is bonded to the crown portion of the base tire. In Precure Tread
In the back portion, a communication groove that connects at least the adjacent back surface grooves is provided,
A precure tread characterized in that a through hole communicating with the communication groove is provided in the grounding surface portion.   The precure tread according to claim 1, wherein the communication groove has a groove depth shallower than the back surface groove.   The precure tread according to claim 1, wherein the through hole is formed in a groove bottom of the surface groove. The communication groove extends in the longitudinal direction of the precure tread and communicates between the back grooves adjacent in the longitudinal direction, and between the communication longitudinal grooves that extend in the inclination direction with respect to the longitudinal direction and are adjacent to the inclination direction. Including a communication lateral groove communicating with
The precure tread according to any one of claims 1 to 3, wherein the through hole is formed so as to communicate with the communication lateral groove.   The precure tread according to claim 4, wherein the surface groove includes a surface lateral groove extending in a direction inclined with respect to a longitudinal direction of the precure tread, and the communication lateral groove is formed at a position corresponding to the surface lateral groove. .   The precure according to any one of claims 1 to 5, wherein the surface groove includes a surface longitudinal groove extending in a longitudinal direction of a precure tread, and the through-hole is provided in a groove bottom of the surface longitudinal groove. tread.   The precure tread according to any one of claims 1 to 6, wherein the back groove is a sipe.

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