JP2721381B2 - Method of manufacturing pneumatic tire with up-down radial carcass structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) Pneumatic tires, especially those used for such purposes as wheels for take-off, landing and taxiing of aircraft, are particularly well-filled with high-pressure air. For a tire that is required to withstand high-speed running, a carcass structure is important as a basis of body reinforcement.

To reduce the weight of this type of tire, attention has been paid to the usefulness of a so-called radial structure carcass, and the applicability of the application is increasing, but it has not yet reached the level of practical use.

The following describes the results of research on development of a method of manufacturing a pneumatic tire with an up-down radial carcass structure, which is suitable as an aircraft tire and can meet the required durability under severe or severe use conditions. .

(Prior Art) In general, a pneumatic tire having a radial carcass structure has a structure in which a belt and a tread rubber are combined during a toroidal deformation of a cylindrical green case in which a ply of a carcass is moored by a pair of bead cores. In the case of high pressure air filling, such as in aircraft tires, the ply pull may be obtained by mooring simply by wrapping the carcass ply around the bead core. I can not stand the omission.

According to the up-down type radial carcass structure using a so-called down ply that winds along the rewind in addition to such a turn-up ply that rewinds, in order to withstand high internal pressure by balancing the tension acting on both plies On the other hand, it is particularly advantageous, but since the deformation resistance when the green case is toroidally deformed is remarkable, wrinkles are generated on the outer surface of the bead portion, which is a starting point of damage.

(Problem to be Solved by the Invention) The rising rotation of the bead portion at the time of toroidal deformation of the green case in the early stage of the green tire building stage,
It is an object of the present invention to provide a method of manufacturing a pneumatic tire of an up-down type radial carcass structure that can fundamentally remove the cause of damage caused by wrinkles on the outer surface of the bead portion by guiding based on the rotational deviation inside the bead core. .

(Means for Solving the Problems) The present invention uses a pair of bead cores to extend a cylindrical green case, which continuously extends between them and anchors a ply of radially arranged carcass, with a bladder capable of expanding and contracting a trunk diameter. This is set on a forming drum consisting of a homer ring that can move relatively close to and away from each other, and after a process of forcing toroidal deformation, a vulcanization mold is formed on a green tire obtained by combining a belt and tread rubber. In the manufacture of tires that are shaped and vulcanized inside, the radial arrangement carcass of the green case described above is turned up and down between the turn-up ply wound around the bead core using cable beads and the down ply along the winding. As for the method, homering is applied to toroidal deformation of the green case due to bladder swelling. While to follow the foot width reduction of green case based on the near mobile, the rotational displacement of the outer layer sheath of the cable bead,
A method of manufacturing a pneumatic tire having an up-down type radial carcass structure, wherein the pneumatic tire guides rising rotation of a bead portion.

1 (a) and 1 (b) illustrate a green case toroidal deformation procedure in a process of manufacturing a pneumatic tire having an up-down type radial carcass structure according to the present invention.

In the figure, 1 is a green case, 2 is a bladder, and 3 is a pair of left and right homerings.

Green Case 1 has two separate, wide and narrow cord strips with rubber coating so that organic fiber cords such as nylon 66 cords (1890 d / 3) are arranged side by side in the width direction. At the width of the former, the former 1a is wrapped around a pair of bead cores, and the latter 1b is adhered in a substantially cylindrical shape on a green case forming drum so as to be in a laminated state overlapping on the rewound, and sidewalls on both sides. The rubber layer 5 and the bead chafer rubber 6 are bonded together, and the former 1a of the cord strip is used for the turn-up ply, and the latter 1b is used for the down ply.

This green case 1 is a bladder 2 that can be expanded and contracted with a trunk diameter.
And a pair of homer rings 3 that can move closer to and away from each other, and are set on a forming drum. The space between the homer rings 3 is reduced while the bladder 2 is inflated, so that the toroidal deformation is performed. In the present invention, the bead core 4 is shown in FIG.
The cable bead shown in (b) is used.

The cable bead is composed of sheath wires 4b, 4c, 4d and 1 to 4 layers around an annular core strand 4a.
4e along a coarse spiral, for example 11,17,23
And an annular helical bundle having 29 ends and abutted at both ends. In the figure, reference numeral 7 denotes a bind wire of a spiral bundle, which can be removed after the entire cable bead is subjected to rubber coating, but may be left as it is. Also, the butted ends of the annular helical bundle of sheath wires can be fixed by a cylindrical sleeve without using a bind wire.

(Operation) Since the cable bead is formed by winding the sheath wire in the above-described multilayer (four layers in the illustrated example), the side wall rubber layer 5 indicated by an arrow in FIG. As the lower region rotates, the sheath wire 4e, and sometimes 4d, 4c, is more rotationally displaced in the outer layer.

Although this rotation deviation angle slightly varies depending on the mold foot width of the green tire and the foot width during toroidal deformation, FIG. 3 shows tire sizes H46 × 17 R20 and H46 × 18.0 R2.
As shown in the example of the result of calculation for the 0 prototype tire, the difference in foot width before and after toroidal deformation (A−
B) Approximately 50-80 ° depending on the change in the width of the foot on one side
About.

In practice, this rotational deviation is almost 80% to 90% in the outermost layer of the sheath wire 4e, and 20% in the adjacent layer of the sheath wire 4d.
% Or less, the distribution is almost 0% in each of the inner layers of the sheath wires 4c and 4b.

EXAMPLES For aircraft radial tires of sizes H46 × 17 R20 and H46 × 18.0 R20, nylon 66 (1890 d
/ 3) A green tire is produced by toroidally deforming an up-down carcass using a cord in the manner shown in FIG. 1, and a bead core is obtained in the same manner using a hexagonal array bead wire 4 'according to the prior art. Also prepare a comparative green tire that can be shaped in the same mold,
When subjected to vulcanization, the comparative tire already had a fold 5 as shown in FIG. 4 in the process of toroidal deformation.

The shaped and vulcanized tires were not only damaged by the method of the present invention, but also did not show any abnormalities or failures even after various tests. Under the wall rubber layer 5, wrinkles were present and the appearance was not rugged. In addition, the dissection of the up ply 1 b was observed in the anatomical examination after the drum durability test.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a toroidal deformation behavior, FIG. 2 is an explanatory view showing an appearance and a partial cross section of a cable core, FIG. 3 is a correlation graph of a foot width and a rotation angle of a bead core, and FIG. It is sectional drawing which shows the generation | occurrence | production behavior of the defect in the toroidal deformation process of an example. 1: Green case 1a: Turn-up ply 1b: Down ply, 2: Bladder 3: Homering, 4,4 ': Bead core

Claims (1)

(57) [Claims] 1. A cylindrical green case having a pair of bead cores and having a ply of a radially arranged carcass extending continuously between them is fixed to a bladder having a trunk diameter which is expandable and contractible, and is positioned relative to each other. It is set on a forming drum consisting of an approachable and distant movable homering, and after a step of forcing toroidal deformation, the green tire obtained by combining the belt and tread rubber is shaped and vulcanized in a vulcanizing mold. In the production of tires to be performed, the radial arrangement carcass of the above green case becomes an up-down system of a turn-up ply wound around a bead core using a cable bead and a down ply along the winding-back, Due to the toroidal deformation of the green case caused by the swelling of the green case, While following the reduction of the foot width of the cable, due to the rotational displacement of the outer sheath of the cable bead,
A method for producing a pneumatic tire having an up-down type radial carcass structure, which guides a rising rotation of a bead portion.