JPH02200423A - Preparation of pneumatic tire having up-and-down system radial tire carcass structure - Google Patents

Abstract

PURPOSE:To fundamentally remove the damage caused by the generation of wrinkles on the outer surface of a bead part by smoothly and stably guiding the rising revolution of the bead part at the time of the troidal deformation of a green case at the initial period of a green tire making stage. CONSTITUTION:A green case 1 is set on a making drum consisting of bladder 2 whose body diameter is expansible and a pair of former rings 3 movable so as to approach the bladder 2 and to be spaced apart therefrom in a state holding said bladder 2 therebetween and the interval between the former rings is contracted while the bladder 2 is expanded to subject the green case 1 to troidal deformation but, especially, a cable bead is used with respect to a bead core 4. This cable bead is composed of an annular spiral bundle wherein sheath wires 4b, 4c, 4d, 4e are respectively wound, for example, 11, 17, 23 and 29 times around an annular core strand 4a over the first-fourth layers along rough spirals in succession and both ends of the respective wires are abutted. The bind wire 5 of the spiral bundle can be detached after the whole of the cable bead is coated with rubber or may be left as it is.

Description

[Detailed Description of the Invention] (Industrial Application Field) Pneumatic tires, especially high-pressure pneumatic tires, such as those used as wheels for aircraft take-off, landing, and taxiing. For tires that are required to withstand high-speed driving, the carcass structure is important as the basis for reinforcing the body.

In order to reduce the weight of this type of tire, attention has been focused on the usefulness of a so-called radial structure carcass, and momentum for its application is increasing, but it has not yet reached the level of practical use.

The following describes the results of research and development on a method for manufacturing an up-down radial carcass pneumatic tire that is suitable for aircraft tires and can meet the required durability under extremely harsh usage conditions. .

(Prior art) In general, radial carcass structure pneumatic tires are manufactured by combining a belt and tread rubber into a tire vulcanizer mold while toroidally deforming a cylindrical green case in which carcass plies are moored by a pair of bead cores. However, when high-pressure pneumatic tensioning is used, such as in aircraft tires, mooring of the carcass ply by simply wrapping it around the bead core does not allow the ply to It cannot withstand pulling out.

In addition to this kind of turn-up ply,
The up-down radial carcass structure using so-called down plies that are wound along the windings is particularly advantageous because it can withstand high internal pressure by balancing the tension acting on both plies. Because of the significant deformation resistance, wrinkles occur on the outer surface of the bead, which can lead to breakage.

(Problem to be solved by the invention) By guiding the rising rotation of the bead part smoothly and stably during toroidal deformation of the green case in the early stage of green tire construction, damage caused by wrinkles on the outer surface of the bead part can be caused. It is an object of the present invention to provide a method for manufacturing an up-down type radial carcass structure pneumatic tire that can fundamentally eliminate the above problems.

(Means for Solving the Problems) This invention provides a cylindrical green case in which plies of a radially arranged carcass are moored by a pair of bead cores, and a bladder that can be inflated and contracted with a body diameter, which is sandwiched between the green case and the bladder so that the plies can be relatively approached and separated from each other. A green tire is set on a forming drum consisting of a movable former ring, undergoes a process of forcing toroidal deformation, and is then combined with a belt and tread rubber.The resulting green tire is shaped and vulcanized in a vulcanization mold. In manufacturing, the radial arrangement carcass of the green case has an up-down method with a turn-up ply wound around a bead core using a cable bead and a down ply along the unwinding. While following the toroidal deformation of the green case due to the diameter and the reduction in foot width of the green case based on the approach movement of the home ring,
This is a method for manufacturing an up-down type radial carcass structure pneumatic tire, characterized in that the rising rotation of the bead portion is guided by rotational deviation of the outer sheath of the cable bead.

FIGS. 1(a) and 1(b) illustrate the procedure for green case toroidal deformation in the manufacturing process of the up-down type radial carcass structure pneumatic tire 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 home rings.

In the green case 1, in the previous stage, we separately installed rubber-coated cord strips in which organic fiber cords such as nylon 66 cord (1890d/3) were lined up horizontally in the width direction. In terms of width, the former 1a is wound around a pair of bead cores, and the latter 1b is laminated on a green case making drum in a layered state overlapping the wound cores, and sidewall rubber is attached on both sides. Layer 5 and bead chafer rubber 6 are pasted together,
The former code strip 1a is used as a turn-up ply, and the latter code strip 1b is used as a down ply.

This green case 1 is set on a forming drum consisting of a bladder 2 whose body diameter can be expanded and contracted, and a pair of homerings 3 that can be moved toward and away from each other with the bladder 2 in between. In particular, in this invention, the bead core 4 is deformed into a toroidal shape by reducing the interval between the bead cores 4 and 4 as shown in FIG. 2(a).
The cable bead shown in (b) is used.

This cable bead extends around the annular core strand 4a and extends over the first to fourth layers of sheath wires 4b, 4c.
, 4d and 4e are made to turn, for example, 11, 17, 23 and 29 times along a rough spiral in order, respectively, and their respective ends are butted to form an annular spiral bundle. In the figure, reference numeral 5 indicates a binding wire of the helical bundle, and although it can be removed after the entire cable bead is coated with rubber, it may be left as is. Furthermore, the abutting portions of both ends of the annular helical bundle of sheath wires can be fixed with a cylindrical sleeve without using a binding wire.

(Function) Since the cable bead is wound with the sheath wire in the above-mentioned multilayers (4 layers in the illustrated example), the sidewall rubber layer 5 shown by the arrow in FIG. 1(b) during the above-mentioned toroidal deformation
As the lower region of the sheath wire 4e rotates, the outer layer of the sheath wire 4e, and sometimes 4d and 4c, undergoes more rotational displacement.

This rotational deviation angle is the mold foot width of the green tire,
Although it varies slightly depending on the foot width during toroidal deformation, the tire size shown in Figure 3 is 1146X17R20, H46.
As shown in an example of calculation results for X1B and 0R20 prototype tires, it is approximately 50 to 80% depending on the change in foot width on one side, which is the percentage of the difference in foot width (A-B) before and after toroidal deformation. It will be about °.

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

Example size n46x17 R20 and old 6x18. OI? 2
According to the present invention, an up-down type carcass using nylon 66 (1890d/3) cord was toroidally deformed in the manner shown in Fig. 1 to produce a green tire for an aircraft radial tire of No. 0. A comparison green tire obtained in the same manner using a hexagonally arranged bead wire 4' according to the above was also prepared, shaped in a similar mold, and subjected to vulcanization. A fold 5 as shown in the figure occurred.

The tires that were shaped and vulcanized by the method of this invention did not have any abnormalities or failures even when subjected to various tests, as well as their appearance.However, the comparative tires broke during toroidal deformation and suffered side damage. There were wrinkles below the wall rubber N5, which looked unsightly, and an anatomical examination after the drum durability test revealed separation in the upply 1b.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of toroidal deformation behavior, Figure 2 is an explanatory diagram showing the appearance and partial cross section of the cable core, Figure 3 is a correlation graph between foot width and bead core rotation angle, and Figure 4 is a comparison. FIG. 3 is a cross-sectional view showing the defect generation behavior during the example toroidal deformation process. ■... Green case 1a... Turn amplifier ply 1b... Down ply 2... Bladder 3...
Homering 4.4'...Bead core Figure 1 (a) (b)

Claims (1)

[Scope of Claims] 1. A cylindrical green case in which plies of a radially arranged carcass are moored by a pair of bead cores is sandwiched between an inflatable bladder having a trunk diameter and a home ring capable of moving toward and away from each other relative to each other. In manufacturing a tire, the green tire is set on a forming drum consisting of and subjected to a process of forcing toroidal deformation, and then the green tire obtained by combining the belt and tread rubber is shaped and vulcanized in a vulcanization mold. Assuming that the radial arrangement carcass of the green case described above is an up-down method with a turn-up ply wound around a bead core using a cable bead and a down ply along the turn-up, the green case is An up-down type radial carcass characterized by guiding the rising rotation of the bead part by rotational deviation of the outer layer sheath of the cable bead while following the narrowing of the foot width of the green case based on the approach movement of the home ring to the toroidal deformation. Method of manufacturing structural pneumatic tires.