JPH02106409A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve warkability and to prevent generation of rigidity difference in the start end and final end of wound roll by providing a multi-cord layer to be wound closely in at least one layer of belt, forming the multi-cord of ribbon composed of respective small bundles being arranged all together. CONSTITUTION:A belt 2 is composed of two sets of fold layers 2a and two sheets of separation layers 2b which layers 2a, 2b are superposed sequentially. Two sheets of separation layers 2c are included inside each of the fold layers 2a, while an additional wound layer 5 is interposed between the fold layers 2a. In this case, the layer 5 is wound in a close roll by using a ribbon-like cord strip which is formed of two small bundles b1, b2 composed of two sets spaced with a step S of at least 50mm at both start and final ends of the roll and arranged all together, and which is coated with rubber. It is thus possible to improve workability as well as to prevent generation of rigidity difference in both the start and final end of the layer 5.

Description

[Detailed Description of the Invention] (Industrial Application Field) Pneumatic tires, especially those used in aircraft wheels for take-off, landing, and taxiing, are used to carry high-pressure air tires to bear extremely high loads. Suppression of so-called standing waves is particularly important when used for low-speed high-speed driving, and the results of research and development of pneumatic tires that can advantageously meet such requirements will be described below.

(Prior Art) The pneumatic tire to be used for the above example has a carcass with a toroidal radial structure that serves as body reinforcement,
The core of the method is to surround the crown of the carcass with cross-layered multiple layers of diagonal cord cloth, and to provide a belt that serves to reinforce the tread.
Close winding of the cord around the layer as much as possible along its circumference (
It is desired that the belt layer contains a cord angle (N) close to 0° with respect to the equatorial plane of the tire.

It is known that in order to create this closely wound layer, a cord strip made of blind weave cloth is cut to match the circumference of the wound layer, and the cut ends are seamed. It is difficult to obtain the necessary strength, and the pressure resistance is not sufficient.

On the other hand, if the winding layer is created using a helical wire that forms a tight spiral using a single rubber-coated cord, there is no problem with pressure resistance or durability, but the number of windings increases, which impairs workability. There are difficulties and costs are affected.

Therefore, if multiple cords are lined up horizontally and coated with rubber to form a flat string shape to create a so-called multi-helix winding layer, the workability will be significantly improved. Therefore, failures occur frequently, so it is not suitable for practical use.

(Problems to be Solved by the Invention) By applying appropriate terminal treatment in the creation of the above-mentioned multi-helix winding layer, the disadvantages of rigidity steps that were conventionally considered unavoidable at the beginning and end of the winding layer can be overcome advantageously. It is an object of this invention to provide a pneumatic tire.

(Means for Solving the Problems) The present invention includes a carcass with a toroidal radial structure for reinforcing the body, and a belt that surrounds the crown of the carcass with intersecting multiple laminations of diagonal cords. The belt comprises a layer of closely wound cord bundles wound around at least one of the layers, the cord bundles having no more than three cord bundles separated by at least 50 steps at the start and end of the helix. A pneumatic tire is a pneumatic tire consisting of a ribbon made of a plurality of small bundles of ribbons arranged flat together, and the cord bundle is a ribbon made of several heat-shrinkable organic fiber cords coated with rubber. It is also more advantageous for the cord bundle to consist of two or three sub-bundles of no more than two cords.

Now, FIG. 1 shows a cross section of a pneumatic radial tire according to the present invention, in which 1 is a carcass, 2 is a belt, 3 is a tread, and 4 is a bead core.

The carcass 1 is preferably an up-down type suitable for use as an aircraft tire, with 1a being a turn-up ply and 1b being a down-ply, both of which are made of organic fibers such as nylon 66 cord (1890d/3). You can use something like code.

In this example, belt 2 has two sets of fold Jii2a,
Two separation layers 2b are stacked one after another, and furthermore, two separation layers 2c are also included inside each fold layer 2a,
Furthermore, a case is shown in which the fold layer 2a is laminated with an additional winding layer 5 interposed between the folds N2a. A relay piece 7 extending between these at each terminal of
Included between. It is preferable that the separation layer 2c has a butt seam J that preferably divides the belt into three parts in the width direction of the belt.

Nylon 66 is also used for each layer used in the lamination of the belt 2.
A heat-shrinkable organic fiber cord such as Cord (1890d/3) is used as a reinforcing element, and cross-layered multiple layers of cord cloth coated with rubber according to the customary method are used. The element is formed into a bundle of several of the above-mentioned cords arranged flat, and is made into a rubber-coated ribbon or flat string (in this example, around the lower fold W2a located directly above the carcass L). It is wound into a spiral shape.

At each butt joint J, it is possible to place a seam filler rubber derived from a rubber strip of the same type as the covering rubber of the reinforcing element, which was disposed along each joint J during the belt lamination stage.

FIG. 2 shows a case in which a bundle of four cords B is used for the winding N5 interposed between the folds i2a of 2WJ in this example of the belt 2 which is multi-layered as described above. Two small bundles b1., each consisting of two bundles, separated by at least 50 steps S at the beginning and end of the helix, as shown in FIG. The bt is pulled together and wrapped in a tight spiral using a ribbon-like cord strip coated with rubber.

The number of small bundles to which step S is attached is divided into two in the illustrated example, but it may be divided into three or more, and the cords belonging to each set of small bundles may be 1-final, complete, or 1 and 2. It is also possible to use these small bundles as a cord bundle B by combining them in the winding process.

(Function) In the present invention, the tightly spirally wound cord bundle is composed of a ribbon-like cord strip made up of several cords, so the winding to form the winding layer requires less rotation and improves workability. In addition, since this cord bundle is divided into small bundles at the beginning and end of the winding layer and has a step S, the cord ends are distributed over the circumference, so there is no local rigidity or eaves area. , there is no problem in terms of belt durability.

It is necessary to separate the steps S by at least 50 mm in order to eliminate a difference in rigidity.

Next, if the number of cords in the cord bundle is not less than a few, i.e. six at most, the angle of inclination with respect to the tire's equatorial plane will become excessive, and the expected effect of suppressing standing waves due to the winding layer will not be achieved. There is a risk that it will be insufficient.

It is preferable to use heat-shrinkable organic fiber cords, such as nylon 66, for the cords of the cord bundle, because the contraction caused by the heat of vulcanization of the tire causes a tightening effect on the belt 2, which contributes to suppressing standing waves.

(Example) Aircraft pneumatic radial tires of size H46X1B and OR20 were prototyped according to FIG. 1. In this case, the structure of the wound layer 5 was categorized as shown in the table below, and workability and durability were compared.

Workability was evaluated based on the time required for winding the winding layer, including the treatment of the terminal part, and the time required for a single cord bundle (comparative example 1) was set as 100. Indicated by index. The pressure resistance is also expressed as an index with the belt breaking pressure of Comparative Example 1 as 100.

Belt durability was measured using a drum testing machine with an internal pressure of 200 PSI.
Speed from OMPM to 225M with load 44200LBS
The takeoff simulation test was repeated 50 times with the load raised to PM and then the load removed, and then the internal pressure was 200 PSI, the load was 442,200, the BS was set at 40 MPM, and the flight length was 3.
After repeating the taxiing test 50 times at 500ft intervals, the tire was dissected and the condition of the helical cord end was examined.

(Effects of the Invention) The present invention significantly improves the workability for constructing a belt, including the winding of the winding layer that occupies the layers of a multi-layered belt, without causing problems in belt durability. Moreover, the effect of suppressing standing waves of the tire by the belt can be advantageously enhanced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a tire according to the present invention, and FIG. 2 is a sectional view of a tire according to the present invention.
FIG. 3 is a schematic diagram of a closely spirally wound cord bundle layer. l... Carcass 2... Belt 3... Tread 5... Winding layer B... Cord bundle
b...Small bundle S...Step

Claims (1)

[Claims] 1. A carcass with a toroidal radial structure for reinforcing the body, and a belt that surrounds the crown of the carcass with cross-layered diagonal cords. a layer of a cord bundle in a close helix wound around at least one layer, the cord bundle having at least
A pneumatic tire characterized by being made of a ribbon made by flattening a plurality of small bundles of three or less ribbons separated by steps of 0 mm. 2. The pneumatic tire according to claim 1, wherein the cord bundle is a ribbon made of several heat-shrinkable organic fiber cords coated with rubber. 3. The pneumatic tire according to claim 1 or 2, wherein the cord bundle consists of two or three small bundles each consisting of two or less cord bundles.