JPH05138763A - Pneumatic spare tire and production thereof - Google Patents

Abstract

PURPOSE:To prevent an occurrence of a sink on the outer surface of a sidewall and effectively prevent the release of a carcass ply from a sidewall rubber by a method wherein at and around a position corresponding to a carcass ply winding end, a ring-form protuberance made of the same rubber material as the sidewall rubber is provided. CONSTITUTION:A sheet of carcass ply 3a, 3b, belt layers 5a, 5b, and a tread part 16 are provided. A maximum tire width W is determined to be 80% or less of that of an object tire. A working internal pressure is determined to be 1.5 times larger than that of the object tire. At and around a position corresponding to a carcass ply winding end 18, a ring-form protuberance 19 made of the same rubber material as a sidewall rubber 7 is provided so as to extend in the circumferential direction of the tire. A maximum thickness (t) of the ring protuberance 19 is determined to be 80% or more of a ply cord diameter. In an area of the ring protuberance 19 in the radial direction of the tire, a minimum wall thickness part of a side wall rubber layer with wall thicknesses t1, t2 which are 1.5-3.0 times larger than the ply cord diameter is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called T-type pneumatic tire for spares and a method for manufacturing the same, and more particularly to realizing weight reduction of the tire.

[0002]

2. Description of the Related Art Conventional T-type spare pneumatic tires have a maximum tire width of about 60-80 with respect to the target tire.
%, The internal pressure is 1.5 to 3.0 times, the outer diameter of the tire is substantially the same as that of the target tire, and the thickness of the tread is 40 to 60 times that of the target tire from the viewpoint of maneuverability and other factors. It is general that the negative ratio is smaller than that of the target tire as well as%.

By the way, in recent years, due to problems relating to environmental pollution, energy saving, etc., technical development for further reducing the weight of a vehicle including tires has become increasingly important, and each industry makes great efforts to reduce the weight. We are paying, and the tire industry is no exception.

The most basic conventional concept for reducing the weight of tires is to reduce the thickness of rubber layers such as tread rubber and sidewall rubber, and at the same time, use a cord layer that is a basic reinforcing material for tires. The use of less or lighter cord material, carcass ply,
Since the cord layer such as the belt layer functions as a kind of pressure resistant container, there is a limit to the reduction of the cord layer unless a new special strong cord emerges. Therefore, in recent years, it has been proposed to reduce the thickness of the rubber layer, particularly the sidewall rubber.

[0005]

However, when the thickness of the sidewall rubber is reduced to a certain value or less, the carcass layer itself expands due to the high internal pressure filling of the tire, and The folded end portion receives tensile force to the inner side in the tire radial direction, and the folded end of the carcass ply is displaced.Therefore, a concave portion is generated on the outer surface portion of the sidewall corresponding to the folded end of the carcass ply. In addition to the deterioration of the appearance of the tire, there is a problem that the carcass ply turn-up end is separated due to the concentration of strain in the recess.

The present invention has been made as a result of studies aimed at solving such problems of the prior art, and an object of the present invention is to achieve a sufficient weight reduction of tires. (EN) A spare pneumatic tire capable of effectively preventing the formation of a recessed portion on the outer surface of a sidewall, and an efficient manufacturing method thereof.

[0007]

A spare pneumatic tire according to the present invention has a side end portion of each of at least one carcass ply located over a bead core, the side end portions of which are arranged around the bead core from the inside to the outside of the tire. The belt layer is provided on the outer peripheral side of the crown portion of the carcass ply, and the tread portion is provided on the outer peripheral side of the belt layer, and the maximum tire width is 80% or less of the target tire. In addition, the inner pressure of the tire is 1.5 times or more that of the target tire, and when the tire diameter is made substantially equal to that of the target tire, the carcass ply hoisting end located on the outermost side of the sidewall in the tire width direction is An annular ridge made of the same rubber material as the sidewall rubber and extending continuously in the tire circumferential direction is provided at the corresponding position and its vicinity. However, the maximum thickness of this annular ridge shall be 0.8 times or more, preferably 1.0 to 1.5 times the ply cord diameter, and 1.5 times the ply cord diameter should be applied to the inner and outer areas of the annular ridge in the radial direction of the tire. ~ 3.0 times,
Preferably, the minimum thickness portion of the sidewall rubber layer having a wall pressure in the range of 2.0 to 2.5 times is provided.

More preferably, the width of the annular protrusion along the surface thereof is in the range of 7 to 15 mm, and more preferably,
The thickness of the tread portion at the tread center portion is set within the range of 40 to 60% as compared with that of the target tire, and the negative rate of the tread tread portion is set to be equal to or higher than the negative rate of the target tire.

Further, in the manufacturing method of the present invention, when manufacturing the tire as described above, all molding is performed by one flat former, and shaping and vulcanization are performed in the vulcanization mold. More preferably in this method, each of the tread rubber and the sidewall rubber is integrally extrusion-molded, and thereafter, the tread rubber and the sidewall rubber are attached to the outer peripheral side of the belt layer.

[0010]

In the spare pneumatic tire of the present invention, the annular ridges made of the same rubber material as the sidewall rubber are provided at the position corresponding to the carcass ply winding-up end and its vicinity, in particular. It is possible to effectively prevent the occurrence of a recessed portion on the outer surface, avoid deterioration of the appearance of the tire, and effectively prevent peeling of the carcass ply winding end from the sidewall rubber.

Here, by forming the material of the annular ridge from the same rubber material as the sidewall rubber, the wall thickness around the ply turn-up end portion is increased,
The strain can be relaxed and peeling can be prevented. In other words, when a different rubber material is used, the wall thickness around the folded back end of the ply becomes thin, and a new strain is generated between the different rubbers to facilitate peeling. On the other hand, the extrusion equipment can be simplified and the workability of the molding operation can be improved.

Further, here, by setting the maximum thickness of the annular projection to be 0.8 times or more the diameter of the ply cord, it is possible to more effectively prevent the occurrence of the recessed portion on the outer surface of the sidewall. That is, when the maximum thickness is less than 0.8 times, when the tire is filled with the internal pressure, a concave portion is formed on the outer surface of the sidewall at a position corresponding to the carcass ply winding end, or a concave portion is externally seen. Even if it does not occur, stress concentration occurs on the winding end of the carcass ply, and peeling off of the winding end is likely to occur.

Further, the annular projection has a wall thickness in the range of 1.5 to 3.0 times the ply cord diameter in each of the inner and outer regions in the radial direction of the tire. By providing the minimum thickness portion of the sidewall rubber layer, the weight of the tire is reduced as expected, and the deterioration of the appearance and the workability of the molding work are sufficiently prevented. In other words, that is
If it is less than 1.5 times, the scratch resistance is significantly reduced, and the unevenness of the ply cord appears on the outer surface of the sidewall to deteriorate the appearance of the tire, and the workability of the molding work is deteriorated, while it exceeds 3.0 times. Therefore, the purpose of reducing the weight of the tire cannot be achieved.

By the way, in this tire, when the width of the annular projection along the surface thereof is in the range of 7 to 15 mm, even if the ply turn-up end position varies due to manufacturing variations, the ply end The thickness of the cord surrounding the part can be secured, and peeling can be prevented.

When the thickness of the tread portion at the tread center portion is set within the range of 40 to 60% of that of the target tire and the negative rate of the tread tread portion is set to be greater than that of the target tire, the wet condition is The weight reduction can be achieved together with the improvement of the exercise performance.

Further, in the manufacturing method of the present invention, since the molding is completed by one-step molding, the equipment cost of the tire molding equipment can be reduced and the tire manufacturing efficiency can be greatly improved.

Further, in this manufacturing method, when the tread rubber and the sidewall rubber are integrally extrusion-molded, the molding man-hours and sticking man-hours of the respective rubbers are effectively reduced, and the tire manufacturing efficiency is improved. Can be greatly improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic line cross-sectional view showing a molded state of a tire according to the present invention. Here, for example, on the outer peripheral surface of the flat former 1 having a substantially cylindrical shape as a whole,
The inner liner 2 with a thickness of 1.3 mm is wrapped around the inner liner 2, and the first and second
The carcass plies 3a and 3b are sequentially wound.

Here, both of these carcass plies 3a and 3b are made of polyester cords having a diameter of 0.5 mm and 1000d / 2, and these cords extend substantially in the tire circumferential direction. The first carcass ply here
3a has a width of 410mm, the second carcass ply 3b has a width of 365m
It has a width of m. By the way, each carcass ply
The side end portions of 3a and 3b are folded back from the inner side to the outer side around each pair of bead cores 4 forming a pair and wound up.

Further, first and second belt layers 5a and 5b made of steel cord having a structure of 1 × 4 are sequentially attached to the outer periphery of the carcass 3 made of two carcass plies 3a and 3b. Then, the cords of the belt layers 5a and 5b are extended in directions opposite to each other with respect to the tire equatorial plane at an angle of 28 ° with respect to the tire equatorial plane.
Here, the first belt layer 5a has a width of 100 mm and the second belt layer 5a
The belt layer 5b has a width of 90 mm.

After that, the tread rubber 6 forming the tread portion and the sidewall rubber 7 forming the sidewall are extruded integrally on the outer periphery of the belt layer 5 composed of the two belt layers 5a and 5b. The molded rubber structure 8 is attached. It is needless to say that the tread rubber 6 and the sidewall rubber 7 may be the same or different in quality, as appropriate, as required. By the way, each of the tread rubber 6 and the sidewall rubber 7 can be separately formed by a separate body without depending on the illustrated example. However, the molding man-hours, the sticking man-hours, etc. of each rubber are taken into consideration. In this case, it is preferable to integrally form it as in the illustrated example.

Reference numeral 9 in the figure indicates a line segment in the tire circumferential direction.
A chafer composed of nylon monofilaments extending in a direction intersecting at an angle of 45 ° is shown, and 10 is a filler arranged on the outer peripheral side of each bead core 4.

After the components have been adhered and the molding has been completed in this way, the laminated structure, that is, the green tire, is removed from the flat former 1 and housed in the vulcanization mold, where the green is placed. While shaping the tire into a toroidal shape, the green tire is vulcanized and molded.

Although the method of molding the tire according to the invention in one step has been described above, the tire is subjected to a general two-step molding method, that is, the carcass layer and the sidewall rubber are first attached. At the same time, it is needless to say that the molding can also be performed by a method of shaping into a toroidal shape and then attaching the belt layer and the tread rubber.

FIG. 2 is a cross-sectional view in the width direction showing a state in which the inventive tire manufactured according to the description with reference to FIG. 1 is assembled to the rim (4T) to be used and filled with an internal pressure of 4.2 kgf / cm ² . ..

This tire has two side end portions wound around the bead core from the inside to the outside of the tire, and two carcass plies 3a and 3b, and the carcass plies 3a and 3b. A tire having two belt layers 5a, 5b and a tread portion 16 made of a tread rubber 6 attached to the outer periphery of the belt layers 5a, 5b, and having a tire maximum width W of 80% of the target tire The tires on the outer surface of each sidewall 17 made of the sidewall rubber 7 are as follows, where the working internal pressure is 1.5 times or more that of the target tire, and the tire diameter D is substantially equal to the target tire. A rubber material of the same quality as that of the sidewall rubber 7 is formed at a position corresponding to the carcass ply winding-up end 18 located on the outermost side in the width direction and a portion in the vicinity thereof so Each annular ridge 19 extending continue to provided maximum thickness t of these annular ridge 19
Is 0.8 times the ply cord diameter, more preferably 1.0 to
1.5 times, and 1.5 to the ply cord diameter in the inner and outer areas of each annular ridge 19 in the tire radial direction.
Meat pressure t ₁ in the range of 3.0 times, more preferably 2.0 to 2.5 times,
The minimum thickness portion of the sidewall rubber layer having t ₂ is provided.

Further, in this example, the width L of each annular projection 19 along the surface thereof is set in the range of 7 to 15 mm, and the thickness t ₀ of the tread portion 16 at the tread center portion is 40 times that of the target tire. The range is up to 60%.

According to the tire configured as described above, as described above, the weight of the tire is sufficiently reduced, and yet the separation of the carcass ply winding end 18 can be effectively prevented.

[Comparative Example] A comparative test regarding the weight of the following invention tire and the conventional tire and the occurrence state of separation on the carcass ply winding end will be described.

Invention tire A tire having a structure shown in FIG. 1 and having a size of T135 / 70 R16, from the tire bead base to the central portion of the annular ridge 19, in other words, to the winding end 18 of the carcass ply 3a. The height H is 55 mm and the other carcass ply
The same height up to the winding end 20 of 3b is set to 35 mm, and the annular protrusion
The maximum stacking t of 19 is 1.8 mm and its width L is 10 mm,
In the respective areas inside and outside the radial direction of the annular ridge 19,
The minimum thickness of the sidewall rubber layer, t ₁ and t ₂ , are both 1.8 mm, the maximum tire width W is 133 mm, and the tread width TW is
100 mm, tread 16 ground contact surface (under internal pressure filling,
Negative ratio is 35% (under a specified load), thickness t ₀ of the tread portion 16 at the tread center is 5.5 mm, and tire diameter D is 602 mm. Here, the target tire is 1.7 kgf / cm ^{2 in} use thickness and 21 tire maximum width.
2mm, tread width 171mm, tread thickness 10mm, sidewall thickness 2.4mm, negative ratio 35%.

Conventional tire A tire of the same size as the invention tire manufactured by the two-step molding method. The tread thickness is 5.5 mm, the negative ratio is 25%, the sidewall thickness is 3.0 mm, and the annular ridge is formed. Not provided. The carcass ply and the belt layer are the same as in the invention tire.

Test method The tire weight was measured under the conditions that the negative ratios of the invention tire and the conventional tire were 25% and 35%, respectively. Regarding the occurrence of separation at the carcass ply winding end, the tire internal pressure was measured. and the 2.6kgf / cm ² (62% of the use internal pressure of T type spare tire ^{(4.2kgf / cm 2)),} 80 load
5kg (TRA maximum load of T 135/70 R 16), 80km / h
The distance traveled until separation occurred when the drum traveled at / h was measured.

Test Results The results of the above tests are shown in Table 1 as index values. Each index value is proportional to the measured value.

[Table 1]

[0034]

As is apparent from the above comparative example, according to the present invention, the weight of the tire is reduced and the separation of the carcass ply winding end can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a schematic line cross-sectional view illustrating a molded state of a tire according to the present invention.

FIG. 2 is a widthwise sectional view illustrating a tire according to the present invention.

[Explanation of symbols]

1 Flat former 2 Inner liner 3a, 3b Carcass ply 3 Carcass 4 Bead core 5a, 5b Belt layer 5 Belt 6 Tread rubber 7 Sidewall rubber 8 Rubber structure 16 Tread 17 Sidewall 18 Carcass ply Roll-up end 19 Annular ridge L width W Tire maximum width t ₀ Tread thickness t Maximum thickness t ₁ , t ₂ Wall thickness

Claims (5)

[Claims] 1. At least one carcass ply whose side end portions are wound from the inside of a tire to the outside around a bead core, a belt layer disposed on the outer peripheral side of the crown portion of the carcass ply, and this belt layer. The maximum tire width is 80% or less of the target tire, the working internal pressure is 1.5 times or more of the target tire, and the tire diameter is substantially the same as that of the target tire. An equalized pneumatic tire, comprising a rubber material of the same quality as the sidewall rubber at a position corresponding to the carcass ply winding-up end located on the outermost side in the tire width direction on the outer surface of the sidewall and in the vicinity thereof. An annular ridge extending continuously in the circumferential direction is provided, and the maximum thickness of this annular ridge is 0.8 times the ply cord diameter or more. The ply cord diameter is 1.5 to 3.0 in the inner and outer radial areas.
A spare pneumatic tire having a minimum thickness portion of a sidewall rubber layer having a double thickness range. 2. The width of the annular projection along the surface is 7
The spare pneumatic tire according to claim 1, wherein the pneumatic tire for spare has a range of -15 mm. 3. The thickness of the tread portion at the tread center portion is set within a range of 40 to 60% of that of the target tire, and the negative rate of the tread tread portion is set to be greater than that of the target tire. Item 1. A pneumatic tire for a spare according to Item 1 or 2. 4. At least one carcass ply whose side end portions are wound around the bead core from the inside to the outside of the tire, a belt layer disposed on the outer peripheral side of the crown portion of the carcass ply, and this belt layer. The maximum tire width is 80% or less of the target tire, the working internal pressure is 1.5 times or more of the target tire, and the tire diameter is substantially the same as that of the target tire. A method for producing a pneumatic tire for a spare tire, characterized in that, when producing equalized pneumatic tires, all molding is performed on a flat former, and shaping and vulcanization are performed in a vulcanization mold. 5. The method for manufacturing a pneumatic tire for a spare tire according to claim 4, wherein each of the tread rubber and the sidewall rubber is integrally extruded.