JPH02106329A - Vulcanization of tire for aircraft - Google Patents

Abstract

PURPOSE:To obtain a uniform rubber gauge around a bead core by preliminarily semivulcanizing or vulcanizing the outer surface of a cover rubber covering the periphery of the core in contact with plys prior to a green case manufacturing step. CONSTITUTION:A green tire 6 is charged in a mold of a tire molding vulcanizing machine, a shaping green tire 6 is strongly pressurized, the cover rubber 2 of a bead core 1 surrounded at its substantially half periphery with the winding region of a turn-up ply layer 7 is compressed during heating from a mold 4 to fluidize the rubber. However, since the rubber 2 of the core 1 is preliminarily semivulcanized or vulcanized on its outer surface opposed to the turnup ply of its carcass, even if it is effected by the shaping pressure in the mold 4 of a tire molding vulcanizing machine during heating, actual rubber fluidization does not occur in the rubber 2, and after the vulcanization is finished, the gage of the rubber 2 is uniformly obtained on the whole periphery of the core 1.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a method for vulcanizing aircraft tires, particularly to improving the durability of the bead portion during use of the tire, and in particular, improving the durability of the carcass cord surrounding the bead core due to fretting. This paper attempts to propose a method for vulcanizing aircraft tires that can contribute to safe aviation operations by increasing resistance.

(Prior art) Japanese Patent Application Laid-Open No. 61-285104 discloses a cord layer in which cords of organic fibers such as nylon, polyester, rayon, etc. are embedded in rubber with specific physical properties in order to cover and protect the area around the bead core of an aircraft tire. Although it has been disclosed that the use of a coating that is made up of more than 100% is actually used within the coating layer due to the bladder pressure that is applied as the tire is shaped? n r
It has the disadvantage that itFJ code disturbances are likely to occur.

(Problems to be Solved by the Invention) Even if the bead core is simply covered with a cover rubber, irregularities in the cover rubber gauge due to rubber 'd+'y' will not occur during tire molding and vulcanization, and the bead core It is an object of the present invention to propose a method of vulcanizing aircraft tires, which makes it possible to secure a rubber gauge of - type around the tire.

(Means for Solving the Problems) This invention provides a layer of turn-up ply for a carcass on both sides of a green case forming drum, and a layer of cover rubber is preliminarily applied to both sides of the drum. Wrap it around the bead core that has been treated with J[, then layer the same layer of down ply to create a green case, transform this green case into a toroidal shape, and pass a belt and tread rubber through the crown area to create a green tire. After that, when vulcanizing in the mold of a tire molding and vulcanizing machine, a preliminary semi-vulcanization or vulcanization treatment is applied to the outer surface of the green case in contact with the cover rubber ply surrounding the bead core. This is a method for vulcanizing aircraft tires, which is characterized in that the vulcanization is performed prior to the vulcanization stage.

In this invention, it is preferable that the pretreatment is performed by radiation irradiation.

Now, Fig. 1 shows a cross section of a bead core 1, which can be made of a cable core, with a cover rubber 2 extending 41 m around the bead core 1, with some cable wires omitted from the illustration.The cable core is made of steel. A steel wire is wrapped around a ring-shaped core wire in multiple layers with coarse reeds. It consists of M number of wire layers.

The cover rubber 2 is attached to the heat core 1 as shown in FIG.
The rubber strip 3 is irradiated with radiation as shown by R from one side before being applied to the rubber strip 3, and then the semi-vulcanized or vulcanized side is removed and the area around the bead core L is exposed as shown in Figure 1. Wrap it around. At this time, rubber strip 3
Since the side in contact with the bead core 1 remains unvulcanized, no particular problem arises in adhesion.

As long as such semi-vulcanization or vulcanization on one side can be carried out, the preliminary treatment may be carried out after the rubber strip 3 is wrapped around the bead core 1.

Although not shown, the bead core 1 coated with the cover rubber 2 pretreated in this way is placed on the green case forming drum immediately before the carcass turn amplifier ply layer is wound on both sides thereof. Apply the layers of the ply as usual.

Regarding the rewinding of the turn-up ply, a green case is made by overlapping the down ply layer and a pair of sidewall rubber layers in accordance with the customary practice.

Note that the sidewall rubber can also be bonded after undergoing the next toroidal deformation.

When the green case is toroidally deformed, a separately prepared composite of a belt and tread rubber is fitted onto the crown part of the green case 2 and combined to form a green tire, which is the same as the normal process.

Now, this green tire is vulcanized in the mold of the tire molding door 6Xi, but at this time, the third
The green tire 6 is strongly compressed by the filling pressure in the bladder 5 (see the arrow) toward the inner surface of the mold 4 whose main part is shown in cross section in the figure, and the green tire 6 is strongly compressed over approximately half a circumference in the rewinding area of the turn amplifier ply seat 7. The bead core 10 surrounded by the cover rubber 2 is compressed under the heat from the mold 4 to cause rubber flow, so there was a disadvantage that the coating thickness of the cover rubber 2 varied. The surface side of the cover rubber 2 facing the layer 7 is semi-vulcanized or vulcanized in advance according to the present invention, so that the cover rubber 2
Although not shown in the figure, even if a bead protection member such as a so-called flin bar is applied inside the layer 7 of the turn-up ply, the above-mentioned rubber & ah does not occur. The same is true.

Note that 8 in the figure is a down ply layer.

(Function) Since the cover rubber 2 of the bead core 1 has undergone preliminary semi-vulcanization or vulcanization scraping on the outer surface facing the layer 7 of the turn-up ply of the carcass,
As for the shape forming inside the bead core 1, the gauge of the cover rubber 2 is uniform over the entire circumference of the bead core 1 after the vulcanization is completed, because no actual rubber 7A is formed on the cover rubber 2 even if it is subjected to pressure and heating. This will be ensured.

1 square size H46X18. A pneumatic aircraft tire of OR20 was prototyped under the following conditions, and after vulcanization, bead core 1 was made.
The rubber gauge between the
Measurements were taken at three locations a, b, and c (average values at 8 equally divided positions on the circumference) in the area shown in the schematic diagram in the figure. Examples 1 and 2 according to the present invention and comparative examples using the conventional method were measured. I made a comparison.

Carcass structure Up/down ply cord type nylon 66 (1890d/3) Bead core carcass structure I X 5 iu+++ (10+
16 + 22 + 28) x 2.2 cover rubber composition NR/IR blend physical properties 100% Mod: 15 kg/cm" Vulcanization conditions temperature 160'C time 95 minutes Pressure 21 kg/cut Pre-treatment of cover rubber is as shown in Table 1 It is.

Next, each prototype tire was subjected to a drum test (internal pressure 200 P) equivalent to taxiing with 120% load applied.
SI, speed 40MPH, load U53040LBs, mileage 35000FT/time) was conducted 15 times, and after this test, the bead portion was cut and measured, and the length of separation along the bead core and the rubber gauge distribution are also listed in Table 2.

Table 1 (Effects of the Invention) According to the present invention, the rubber gauge between the bead core and the turn-up ply layer of an aircraft pneumatic radial tire having a radial cord arrangement carcass structure, especially an up-down type, is Shading using a conventional molding and vulcanizing machine is properly ensured by suppressing rubber flow during vulcanization, and has a significant effect on improving the bead durability of this type of tire.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the bead core, Figure 2121 is an explanatory diagram of the pre-vulcanization requirements for the rubber strip, Figure 3 is an explanatory diagram of deformation behavior within the forming vulcanization mold, and Figure 4 is a rubber gauge measurement procedure. It is an explanatory diagram. l...Bead core 2...Cover rubber 3.
... Rubber strip 4 ... Mold 5 ... Bladder 6 ... Green tire 7 ... Turn-up ply layer 8 ... Down ply layer Patent applicant Bridgestone Corporation Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. On the green case building drum, a layer of turn-up ply for the carcass is wound around a bead core that has been covered with cover rubber in advance on both sides thereof, and then a layer of down ply is also applied. A superimposed green case is made, this green case is toroidally deformed, and a belt and tread rubber are applied to the crown area to create a green tire.Then, when vulcanizing in the mold of a tire molding and vulcanizing machine, A method for vulcanizing an aircraft tire, the method comprising performing a preliminary semi-vulcanization or vulcanization treatment on the outer surface side in contact with a ply of cover rubber surrounding a bead core, prior to the step of forming a green case. 2. The vulcanization method according to claim 1, wherein the pretreatment of the cover rubber is by radiation irradiation.