JP4587377B2 - Aircraft rehabilitation tires - Google Patents

Description

  The present invention relates to an aircraft retread tire (hereinafter, also simply referred to as “tire”), and more particularly to a tire used in an aircraft such as a jet passenger aircraft, and in particular, to improve the heat resistance and groove crack resistance of a tread. It relates to the rehabilitated tire for aircraft.

  In general, there are two types of aircraft tires: a bias tire having a carcass bias structure and a radial tire having a radial structure. Among these, the bias tire has a cushion rubber layer for protecting the carcass ply from external damage and a fabric layer formed by obliquely arranging one or two layers of organic fibers on the outer side of the bias carcass ply in order from the inner surface side. Further, the tread surface portion includes a tread having a circumferential straight groove.

  The radial tire has a plurality of belt plies on the outer side of the radial carcass ply. In order to protect the belt ply from damage, the cushion rubber layer and one layer of cord are sequentially waved on the outer side from the inner surface side. And a fabric layer formed by arranging one or two layers of organic fibers at an angle, and a tread having a circumferential straight groove on the tread surface. It has the structure provided. These aircraft tires are usually removed from the fuselage and replaced with new ones when the tread groove on the tread portion disappears due to wear. At this time, the removed worn tire is reused as a retread tire by replacing the tread with a fabric layer such as a reinforcement fabric or a cut protector.

  By the way, in a conventional aircraft tire, a so-called cap-base structure tread, which is used in a pneumatic tire for a passenger car or a truck / bus, is not used. This is because, in aircraft tires that require ultra-high speed and high load capacity, groove cracks occur at the groove bottom of the circumferential groove due to a rigidity step at the interface between the cap tread layer and the base tread rubber layer. In other words, a tread composed of a single tread rubber layer that does not have such a risk has been used for aircraft tires.

On the other hand, Patent Document 1 discloses an aircraft tire to which a cap-base tread is applied. However, in this document, since no consideration is given to a rigidity step, occurrence of groove cracks and separation failure are likely to occur. The above-mentioned problem remains, and the region occupied by the base tread rubber is not disclosed at all.
Japanese Patent Laid-Open No. 2-185806

  In recent years, with the increase in size of aircraft, an increase in load resistance capacity has been required for aircraft tires, and a tread structure composed of a single layer cannot cope with heat resistance. Therefore, it is desired to realize an aircraft tire that can further improve heat resistance and the like and does not cause other problems. In particular, in the case of aircraft tires, it is necessary to consider the retreading technology after wear under the above-described circumstances.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aircraft retread tire that improves the heat resistance and durability of a tread and solves the above-mentioned problems without causing other problems such as the occurrence of groove cracks and a method for manufacturing the same. It is in.

  As a result of intensive studies, the present inventor applied the cap-base structure to the tread, and prescribed the locations where the base tread layer was arranged, thereby preventing the occurrence of other problems associated with the application of the cap-base structure. However, the inventors have found that it is possible to improve heat resistance and the like, and have completed the present invention.

That is, the aircraft retread tire of the present invention includes a bead core provided in a pair of left and right bead parts, a carcass extending from the crown part to both bead parts through both sides, wound around the bead core and moored in the bead part. And a tread disposed on the outer side in the tire radial direction of the carcass, and in a rehabilitated tire for an aircraft in which a plurality of linear circumferential grooves are provided on a tread surface portion of the tread,
The tread is composed of a cap tread layer and a base tread layer, the base tread layer is divided and arranged in the tire width direction avoiding the formation position of the linear circumferential groove, and the base tread layer The outer side surface in the tire radial direction is located on the inner side in the tire radial direction from the bottom surface of the linear circumferential groove.

In the present invention, it is preferable that the separation distance between the tire axial direction end portion of the base tread layer that is divided and the adjacent linear circumferential groove is in a range of 0.8 to 6 mm, The cap tread layer and the base tread layer are represented by the following formulas (1) and (2),
1.05 <M (50) b / M (50) c ≦ 1.30 (1)
1.04 <Rb / Rc ≦ 1.20 (2)
(Where M (50) b and M (50) c represent the 50% modulus of the base tread rubber and cap tread rubber, respectively, and Rb and Rc represent the resilience of the base tread rubber and cap tread rubber, respectively) It is also preferable to satisfy the relationship represented by:

  Further, the aircraft retread tire manufacturing method of the present invention is the aircraft retread tire manufacturing method described above, wherein a new base tread layer and a cap tread layer are added to the base tire from which the tread after wear is removed by buffing. Are sequentially stacked and arranged.

  In the production method of the present invention, when the cap tread layer is formed, the cap tread layer is formed by laminating the narrow belt rubber ribbons, and the narrow belt rubber ribbons are formed in the recessed portions between the base tread layers arranged separately. A method of laminating a large number of layers, a method of pasting a cap tread rubber on the base tread layer and the filling rubber after filling the same rubber as the cap tread rubber into the recessed portions between the base tread layers arranged in a divided manner And the lower side surface of the cap tread rubber is formed into a shape having a plurality of convex portions corresponding to the recessed portions between the base tread layers arranged by being divided, and the cap tread rubber is arranged by being divided. Any of the methods of pasting so as to fill in the recessed portions between the base tread layers should preferably be used. It can be.

  According to the aircraft retread tire of the present invention, the above configuration prevents the occurrence of groove cracks due to the interface between the cap tread layer and the base tread rubber layer, while maintaining other performances. It has become possible to improve the heat durability. Further, the aircraft retread tire of the present invention can be easily manufactured by the manufacturing method of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 shows a left-half partial cross-sectional view in the vicinity of a crown portion of an aircraft retread tire according to a preferred embodiment of the present invention. As shown in the figure, the aircraft retread tire according to the present invention includes a bead core (not shown) provided on a pair of left and right bead parts, and extends from the crown part to both bead parts via both sides and wound around the bead core. A carcass (not shown) moored in the bead portion, and a tread 1 disposed on the outer side in the tire radial direction, and a plurality of linear circumferential grooves 3a on the tread portion of the tread 1; 3b is provided. Further, in the illustrated example, two fabric layers 4 are provided between the carcass and the tread 1.

  In the tire according to the present invention, the tread 1 includes the cap tread layer 11 and the base tread layer 12, and the base tread layer 12 is divided in the tire width direction while avoiding the formation positions of the linear circumferential grooves 3a and 3b. And the outer surface in the tire radial direction is located on the inner side in the tire radial direction from the bottom surface of the linear circumferential grooves 3a and 3b. By placing the base tread rubber below the groove bottom of the linear circumferential grooves 3a and 3b, avoiding the positions where the linear circumferential grooves 3a and 3b are formed, the load input to the base tread rubber is reduced. It has become possible to suppress the occurrence of groove cracks.

  Here, the separation distance x between the tire axial direction end portion of the base tread layer 12 that is divided and the adjacent linear circumferential groove 4 is preferably 0.8 to 6 mm, more preferably 1 Within the range of 2 to 4.0 mm. When the separation distance x is less than 0.8 mm, there is a high risk that the interface between the cap tread layer 11 and the base tread layer 12 is exposed on the groove side wall of the linear circumferential groove 3, which is preferable from the viewpoint of ensuring the groove crack resistance. Absent. On the other hand, if the separation distance x exceeds 6 mm, the volume of the base tread layer 12 introduced for improving heat resistance is insufficient, which is not preferable from the viewpoint of ensuring heat resistance.

In the present invention, the cap tread layer 11 and the base tread layer 12 are represented by the following formulas (1) and (2),
1.05 <M (50) b / M (50) c ≦ 1.30 (1)
1.04 <Rb / Rc ≦ 1.20 (2)
(Where M (50) b and M (50) c represent the 50% modulus of the base tread rubber and cap tread rubber, respectively, and Rb and Rc represent the resilience of the base tread rubber and cap tread rubber, respectively) It is preferable to satisfy the relationship represented by these. By defining the physical property ratio of the base tread rubber and the cap tread rubber constituting the base tread layer 11 and the cap tread layer 12 as described above, even if the circumferential groove depth provided on the surface of the tread 1 is increased, The heat generation of the tread 1 can be reduced, whereby the tread is not blown even if the indoor take-off test is repeated, and the effect of improving the number of landings per tread can be obtained.

  In the above formulas (1) and (2), the 50% modulus ratio between the base tread rubber and the cap tread rubber is larger than 1.05 and the resilience ratio is larger than 1.04. This is because strain concentrates on the base tread layer 11 and the base tread rubber blows. In addition, the 50% modulus ratio between the base tread rubber and the cap tread rubber was set to 1.3 or less and the resilience ratio was set to 1.20 or less. This is because the difference in rigidity between the two becomes large and breakage at the interface tends to occur.

Further, the thicknesses Gb and Gc of the base tread rubber and the cap tread rubber are regions of 90% or more of the width of the fabric layer 4 except for the portion directly below the linear circumferential groove 3 and occupied by the groove width. In the following formula (3),
0.15 ≦ Gb / (Gb + Gc) ≦ 0.50 (3)
It is preferable to satisfy the relationship represented by these. If the ratio of the thickness Tb of the base tread rubber to the total thickness Gb + Gc of the tread 1 is less than 0.15, the effect of reducing heat generation is small, whereas if it exceeds 0.50, the wear resistance is reduced. It is. Here, the thickness Gb of the base tread rubber is a thickness from the interface between the base tread rubber and the cap tread rubber to the interface of the coating rubber of the fabric layer 4, and the thickness Gc of the cap tread rubber is the thickness of the new tire. The thickness from the surface to the interface between the base tread rubber and the cap tread rubber. The reason why the region is 90% or more of the width of the fabric layer 4 is to obtain a good effect of the cap-base structure according to the present invention.

  Furthermore, as specific physical property values of the cap tread rubber, in addition to appropriate wear resistance, from the viewpoint of securing chevron cut resistance and chipping resistance, 50% modulus M (50) c is 1. 5 to 1.7 MPa, 3.0% to 3.3 MPa for 100% modulus M (100) c, 50 to 52 for resilience Rc, 0.9 to 1.2 MPa for dynamic storage modulus E ′ It is preferable to be inside.

  The present invention can be applied to both the bias tire and the radial tire described above. For example, when the tire according to the present invention is a bias tire, it is not illustrated, but the gap between the carcass and the fabric layer 4 is not illustrated. A cushion rubber layer is provided as appropriate. When the tire of the present invention is a radial tire, although not shown, a belt layer and a cushion rubber layer are appropriately provided between the carcass and the fabric layer 4. In the tire of the present invention, the cap-base structure is applied to the tread 1, and the points other than defining the arrangement position of the base tread layer 12 as described above are not particularly limited. Other tire structures The material and the like can be appropriately configured according to a conventional method.

  When manufacturing the retreaded aircraft tire of the present invention, a new base tread layer and a cap tread layer are sequentially laminated on the base tire from which the tread after wear is removed by buffing. That is, when the fabric layer 4 is disposed as shown, the tread 1 including the fabric layer 4 is removed (dotted line portion A in the figure), and the crown portion of the obtained base tire is supplementarily added. The new fabric layer 4, the base tread layer 12, and the cap tread layer 11 are sequentially laminated and disposed through the new rubber layer disposed in the above.

  In particular, in the tire structure of the present invention, the base tread layer 12 is divided and arranged in the tire width direction. Therefore, when the cap tread layer 11 is arranged, for example, it is formed by laminating a narrow band-shaped rubber ribbon. The method is preferably used. That is, the cap tread layer 11 is formed on the base tread layer 12 by superimposing a hot narrow rubber ribbon extruded from an extruder. In this case, it is possible to fill the dents by laminating more narrow band-like rubber ribbons than the other parts in the dents between the base tread layers 11 arranged in a divided manner, and thereby the air between the base tread layers 12 can be filled. Can be removed. If air remains in the product, peeling may occur from that portion, and the intended purpose of the present invention may not be achieved.

  In addition, a method in which the concave portion between the base tread layers 12 is filled with the same rubber as the cap tread rubber in advance, and then the cap tread rubber is cold pasted and molded on the base tread layer 12 and the filled rubber is also preferable. Can be used. Here, “cold” means a state where the cap tread rubber extruded from the extruder is air-cooled to room temperature. Further, the lower surface of the cap tread rubber is formed into a shape having a plurality of convex portions corresponding to the recessed portions between the base tread layers 12 arranged by being divided, and the cap tread rubber is formed into the base tread layer 12. A method of pasting so as to fill the recesses between them is also suitable. Also by using these methods, the air between the base tread layers 12 can be surely removed, and the occurrence of problems due to residual air can be prevented.

Hereinafter, the present invention will be described specifically by way of examples.
(Example, Comparative Examples 1 and 2)
Test tires having the tire size H44.5 × 16.5-21 28PR having the cap-base structure shown in FIGS. The arrangement of the base tread layer in the tire width direction and the tire radial direction, the arrangement form of the base tread layer, the separation distance between the base tread layer and the linear circumferential groove, and the physical property values of the cap tread rubber and the base tread rubber are as follows: As shown in Table 1 below. Moreover, the measuring method of each rubber physical property value is as showing below.

(Measurement of modulus)
For both the cap tread rubber and the base tread rubber, the tensile stress at 50% elongation was measured according to JIS K 6251-1993 using a JIS dumbbell-shaped (3) type test piece at a test temperature of 24 ± 2 ° C. This was the 50% modulus.

(Resilience measurement)
Both the cap tread rubber and the base tread rubber were measured at a test temperature of 24 ± 2 ° C. based on a rebound resilience test method according to JIS K 6255-1996.

  The obtained test tires were repeatedly subjected to taxi tests and take-off tests under the following conditions. The results are also shown in Table 1 below.

(Test conditions)
1) Taxi test Load: 1.5 times the rated load Internal pressure: Rated internal pressure Speed: 30MPH
Mileage: 10000ft
2) Takeoff test Load: 1.5 times the rated load Internal pressure: Rated internal pressure Takeoff speed: 260MPH
Takeoff time: 35 seconds 3) Interval between taxi test and takeoff test: within 2 minutes 4) Number of tests 50 times

  As shown in Table 1 above, it was confirmed that in the retreaded aircraft tire of the example to which the present invention was applied, excellent high-speed durability was achieved while preventing the occurrence of groove cracks.

It is a left half partial sectional view near the crown part of the rehabilitation tire for airplanes concerning one suitable embodiment of the present invention. It is a left half partial sectional view of the crown part vicinity of the retreaded aircraft tire according to Comparative Example 1. It is a left half partial sectional view near the crown part of the retreaded aircraft aircraft according to Comparative Example 2.

Explanation of symbols

1 Tread 3a, 3b Circumferential groove 4 Fabric layer 11 Base tread layer 12 Cap tread layer

Claims (7)

A bead core provided in a pair of left and right bead parts, a carcass extending from the crown part to both bead parts through both sides, wound around the bead core and moored in the bead part, and disposed outside the carcass in the radial direction of the tire An aircraft retread tire provided with a plurality of linear circumferential grooves on the tread surface portion of the tread,
The tread is composed of a cap tread layer and a base tread layer, the base tread layer is divided and arranged in the tire width direction avoiding the formation position of the linear circumferential groove, and the base tread layer An aircraft retread tire, wherein a tire radial direction outer side surface is located on a tire radial direction inner side than a bottom surface of the linear circumferential groove.   2. The aircraft rehabilitation according to claim 1, wherein a separation distance between a tire axial direction end portion of the base tread layer arranged in a divided manner and the adjacent linear circumferential groove is within a range of 0.8 to 6 mm. tire. The cap tread layer and the base tread layer are represented by the following formulas (1) and (2),
1.05 <M (50) b / M (50) c ≦ 1.30 (1)
1.04 <Rb / Rc ≦ 1.20 (2)
(Where M (50) b and M (50) c represent the 50% modulus of the base tread rubber and cap tread rubber, respectively, and Rb and Rc represent the resilience of the base tread rubber and cap tread rubber, respectively) The rehabilitated tire for aircraft according to claim 1 or 2, satisfying a relationship represented by:   A method for manufacturing an aircraft retread tire according to any one of claims 1 to 3, wherein a new base tread layer and a cap tread layer are sequentially formed on the base tire from which the tread after wear is removed by buffing. A method for manufacturing retreaded aircraft tires, characterized by stacking.   The method for producing a rehabilitated tire for an aircraft according to claim 4, wherein the cap tread layer is formed by laminating a narrow band-shaped rubber ribbon, and a large amount of the narrow band-shaped rubber ribbon is stacked in a recessed portion between the base tread layers that are divided and disposed. .   The aircraft tread according to claim 4, wherein the recessed portion between the divided base tread layers is filled with the same rubber as the cap tread rubber, and then the cap tread rubber is pasted on the base tread layer and the filled rubber. Manufacturing method for retreaded tires.   The lower surface of the cap tread rubber is formed in a shape having a plurality of convex portions corresponding to the recessed portions between the base tread layers arranged by being divided, and the cap tread rubber is divided and arranged by the base The manufacturing method of the retreaded aircraft tire of Claim 4 stuck so that the recessed part between tread layers may be filled up.

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