JPH02198829A - Preparation of belt of pneumatic radial tire - Google Patents

Abstract

PURPOSE:To eliminate the decrease in productivity and to prevent a cord bundle from occurrence of waving caused by tolerance of winding diameter by performing simultaneously arranging in parallel and flatly bundling several pieces of heat shrinkable org. fiber cords and winding them spirally on a belt forming drum or a preformed under-belt layer on the drum. CONSTITUTION:When a parallel cord strip 8 prepd. by arranging in parallel e.g. four org. fiber cord, bundling flatly them and coating them with a rubber coating is wound on a belt forming drum which is strongly curved on both sides, by using a heat shrinkable org. fiber cord which as e.g. a nylon 66 cord, is a material with a heat-shrinkage of about 4-12% at vulcanization temp. of a tire before vulcanization and after dipping treatment. A vulcanization molding without occurrence of waving on both ends of a spirally arranged cord layer 5 is realized by a heat shrinkage generated when a green tire wherein a tread rubber ring consisting of a belt laminate 2 and a tread rubber 3 is combined with a green case is vulcanization-molded in a tire mold.

Description

[Detailed Description of the Invention] (Industrial Application Field) Radial array bridle tires are used as pneumatic tires, such as aircraft wheels, which can handle high speeds and high loads, and are also lightweight. Up-down type radial tires are especially useful, but in this case it is particularly desirable to improve the belt for trend reinforcement, and in this regard, especially with the aim of improving productivity, air This paper attempts to propose a method for making belts for radial tires.

(Prior Art) When a green case having a carcass made of radially arranged cord plies undergoes toroidal deformation, a tread rubber ring is combined with the green case so as to surround the carcass and integrate to form a green tire. The so-called two-stage molding method, in which tires are separately produced, has become common as a manufacturing method for radial tires.

It is advantageous to incorporate in this tread rubber ring a helical spirally arranged cord as a reinforcing layer of the belt, which is to serve as a tread reinforcing element.

Conventionally, virtually non-stretchable steel cords or polyamide fiber (Kevlar) cords have been used as single windings for this helical arrangement cord, but this is extremely disadvantageous in terms of production efficiency.

On the other hand, if several of the above-mentioned cords are aligned and bundled flat, and multiple spiral windings are performed at the same time, the winding will occur along the periphery of the crown part of the carcass after toroidal deformation, especially in the strongly curved profile on both sides of the periphery. This difference causes the cord bundle to wave on the small diameter side, and the reinforcing effect of the cord is diminished accordingly.

(Problem B to be solved by the invention) Regarding the construction of belts using helically arranged helical cords, winding can be performed without reducing productivity and without causing waving in the cord bundle due to diameter differences. It is the purpose of this invention to propose a method of construction.

(Means for Solving the Problems) This invention provides a green case having a carcass made of radially arranged cord plies, which is assembled into one body in a toroidal deformation arrangement surrounding the carcass, and is used for molding a green tire. When molding the tread rubber ring, a belt made of spirally arranged cords is inserted into the tread rubber ring as a tread reinforcing element.
When incorporating a strongly curved profile along the crown periphery of the carcass after toroidal deformation, especially on both sides of the periphery, several heat-shrinkable organic fiber cords are aligned and bundled flat, and at the same time, the belt forming drum or the This is a method of making a belt for a pneumatic radial tire, which is characterized by performing spiral winding on an underbelt layer that has been prepared in advance on a drum.

Now, FIG. 1 shows a cross section of a pneumatic tire for aircraft using a belt made according to the present invention, in which 1 is the carcass, 1a is the turn-up braai, ib is the down brai, 2 is the belt laminate, 3 is a tread rubber, 4 is a bead core, 5 is a spirally arranged cord layer interposed between the fold layers 2a and 2b in this example, and 6 is a side rubber.

In this example, the helical alignment layer 5 includes, in addition to the fold layers 2a and 2b, an additional outer layer 2c and fold layers 2a and 2b.
Although the case where the belt laminate 2 is formed together with the additional inner layer 2d wrapped in the belt is shown, the belt laminate 2 may also be formed by several layers of only the spirally arranged layer 5.

In any case, the belt laminate 2 is separately formed on a belt building drum 7 as shown in FIG. A tread rubber ring (not shown) is prepared by laminating the tread rubber 3 in sequence, and a green case is fitted into the ring and integrated by toroidal deformation to obtain a green tire.

As is customary, this green tire is molded and vulcanized in a tire mold.

The spiral array layer 5 is wound on the fold layer 2a as shown in FIG. 1, or directly on the belt forming drum 7 as shown in FIG. However, at this time, the diameter of the winding becomes smaller at the beginning and end of the winding than in the middle region, because the crown periphery of the carcass 1 after toroidal deformation is curved more strongly on both sides. This is because

(Function) When winding, for example, four organic fiber cords aligned and flatly bundled and rubber-coated parallel cord strips 8 on a belt forming drum with strong curvature on both sides as shown in Fig. 2,
When a non-stretchable cord is used, it does not fit well as shown in Fig. 3(a), (b), and (c) depending on the above-mentioned curvature, and it cannot be made to follow the drum curvature.
In this invention, in particular, by using a material such as a heat-shrinkable organic fiber cord, such as a nylon 66 cord, which has a heat-shrinkability of about 4 to 12% at the tire vulcanization temperature before vulcanization and after dip treatment, the above-mentioned Waving occurs at both ends of the spirally arranged cord layer 5 due to heat shrinkage during vulcanization molding of a green tire in which a tread rubber ring consisting of a belt laminate 2 and tread rubber 3 is combined with a green case in a tire mold. This allows vulcanization molding to be performed without any blemishes.

EXAMPLE A pneumatic radial tire for aircraft using the belt laminate 2 shown in FIG. When the alignment layer 5 was wrapped, an anatomical test after tire vulcanization showed that no ear waves were generated on the side edges, but Kevlar 3000 d/3
Many ear waves were observed under similar operations using the same cords, demonstrating the usefulness of this invention over the prior art, which required unproductive winding with a single cord. It was done.

(Effects of the Invention) According to the present invention, a radial tire having a carcass made of radially arranged cord ply, which is easy to reduce weight, is intended to be used for applications such as aircraft wheels, which have severe usage conditions in terms of high speed and high load. To easily create a belt with high productivity and without any adverse effects caused by a helical spirally arranged cord layer, which is necessary for tread reinforcement, which is important when carrying out tread reinforcement.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a radial aircraft tire, FIG. 2 is an explanatory diagram of the procedure for winding a spirally arranged cord layer, and FIG. 3 is an explanatory diagram showing the state of nonconformity. 1... Carcass 2... Belt laminate 3.
...Tread rubber 4...Bead core 5...Spiral array cord layer 6...Side rubber 7...Belt forming drum 8...Code strip

Claims (1)

[Scope of Claims] 1. Tread rubber that is combined to form a green tire so as to surround the carcass during toroidal deformation of a green case having a carcass made of radially arranged cord plies. In forming the ring, a belt made of helical spirally arranged cords as a tread reinforcing element is placed in the tread rubber ring and strongly curved along the periphery of the crown portion of the carcass after the toroidal deformation, especially on both sides of the periphery. In the case of assembling with a profile, several heat-shrinkable organic fiber cords are aligned and bundled flat, and at the same time, spiral winding is performed on a belt forming drum or an underbelt layer prepared in advance on the drum. , Belt construction method for pneumatic radial tires.