JPH02106331A - Manufacture of band for carcass of pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the separation resistance and pressure resistance performance of a carcass ply by applying a rubber sealing sheet of the same type as that of covering rubber of a cord stripe onto a butt connecting seam, then stitching them, and maintaining a well-balanced cord array of the stripe. CONSTITUTION:When a rubber-coating stripe to be filled in a carcass ply is sequentially wound to be laminated around a case band forming drum 1 in response to the type of the ply, a sealing sheet 3 made of rubber of the same type as that of the coating rubber of the cord stripe is applied onto the butt connecting seam 4 of the starting end and finishing end of windings of the stripe occupying at least the innermost side and/or outermost side of the carcass, and then stitched. Thus, the cord array of the stripe including the seam 4 is kept well-balanced through the steps of molding a green case and a green tire as well as shaping and vulcanizing subsequent to the formation of a case band 2.

Description

[Detailed description of the invention] (Industrial application field) Among radial tires, such as aircraft wheels,
For large tires intended for applications that require extremely harsh operating conditions under high internal pressure and large loads, the carcass structure, which is the basis of body reinforcement, is fundamentally important. This is particularly important from the perspective of safe operation.

The molding process for this type of tire generally involves making a green case, going through a green tire molding process that includes toroidal deformation, and then vulcanizing the shape in the mold of a tire molding and vulcanizing machine. However, in the pre-forming stage of the green case, rubberized cord strips for carcass plies are first wrapped and laminated around the band forming drum in sequence for each type of ply (for example, turn-up ply, turn-down ply, etc.). , a so-called band formation stage is included.

At this stage, it is difficult to expect a sufficiently high joint strength at the joint between the starting end of the cord strip and the ending end of the winding, which is a cause that prevents the application of radial structure carcass to large tires such as those for aircraft wheels. Therefore, we would like to propose a carcass band forming method that provides a simple and effective solution to this problem.

(Prior Art) Japanese Patent Application Laid-Open No. 63-98424 discloses that a cord strip is wound by pushing a narrow cord-containing material along the butt joints at the beginning and end. This results in an imbalance in cord tension.

(Problem to be Solved by the Invention) In the pasting process of rubberized cord strips on a band forming drum, the seam connection between the starting end of the IJ tube and the ending end of the winding is performed with respect to the innermost ply. The inner liner, which is pre-wound on the mold release agent layer on the surface of the drum directly below, gets into the widened cord gap at the above seam, causing separation due to the mold release agent mixing with the inner liner. As for the outermost ply, there is a concern that the local strength reduction due to widening of the cord gap during the toroidal deformation process after the green case forming stage will become the core of tire burst.

Therefore, it is an object of the present invention to provide a carcass band construction method that can appropriately suppress the widening of the cord spacing at the seam as described above.

(Means for Solving the Problems) The above objectives are advantageously achieved by a configuration that includes the following points.

When forming a green case for a pneumatic tire that has a radial structure carcass as body reinforcement, rubberized cord strips for the carcass fly are sequentially wrapped around the case band forming drum according to the ply type and layered. , at least the innermost part of the carcass and/or
Or, the winding of the cord strip occupying the outermost side is the starting end,
Wrapping is carried out by pasting a stitching sheet made of the same type of rubber as the covering rubber of the code strip on the butt joint seam with the end, and then stitching is performed, and this is followed by the creation of this case band. The molding and shaping of green cases and green tires is done through the vulcanization process.
A method for making a band for a carcass of a pneumatic tire, characterized by maintaining a uniform cord arrangement of the strips including butt joint seams.

In this invention, the cord type used for the rubberized cord strip is 1260 nylon, aramid cord, etc.
d/3.1890d/2.1890d/3 (nylon).

It is suitable for a twisted structure such as 1500a/2.3000d/3 (aramid) with a driving density of about 50 to 75%, and the type of covering rubber is natural rubber, or a combination of natural rubber and some synthetic rubber. Mooney viscosity 40-70
It is desirable to use it under physical properties such as kg/m.
The same applies to the stitched sheet.

(Function) By using the same type of rubber as the cord covering rubber for the stitching sheet, the overall homogeneity of the band is not impaired, and in this sense, the thickness and width of the stitching sheet are
0.2 each for rubberized cord strip gauge
~0.8 mm, preferably in the range of 7 to 20 m + 11 meters, and by passing through the case band creation stage in which such a stitching sheet is pasted on the butt joint seam and stitched, The green case and green tire are formed and shaped using this band without causing any disturbance in the arrangement of the strip cords including the butt joints during the vulcanization process.

Embodiment FIG. 1 shows the procedure for laminating the stitching sheet to the butt joint seam on the hand-forming drum of a case band according to the present invention, in which 1 is the band-forming drum, 2 is
3 is a case band, 3 is a stitching sheet, and 4 is a butt joint seam.

In accordance with the customary practice, the butt joint seam 4 is formed with a diagonally shaved cut end as shown in the figure at the center of the driving interval of the cords 5, so that the intervals between the cords sandwiching the joint are even. The diagonal cut was 60° in this example.

The gauge of the cord strip used for the case band 2 in this example was 1.3 mm, so the stitching sheet 3 was made of an unvulcanized rubber strip with a thickness of 0.4 mm and a width of 10 mm that matched the gauge of the cord strip used for the case band 2. They were pasted along the seam 4 in the width direction.

Although it is not shown in the figure, this stitching sheet 3 is applied to the innermost cord strip in contact with the inner liner that has been wrapped in advance around the band forming drum 1, and on top of this, the cord strips are sequentially attached for each ply type. Each layer was applied to the outermost cord strip and then stitched to obtain a case band.

This case band 2 is manufactured by the following process: green case molding, green tire molding with continued toroidal deformation, and shaping by a bladder in the mold of a tire molding and vulcanizing machine. No disturbance occurred.

(Effect of the invention) When the cord strip used for the ply that constitutes the carcass, which is important for reinforcing the body of the tire, is wound around a band forming drum to obtain a case band, the cut ends of the cord strip are butt-joined along the joint. At least the innermost and outermost parts of the case band are pasted with a stitching sheet, and the formation of the green case and green tire that follows the creation of this case band, as well as their shaping, are carried out by the above-mentioned butt-bonding process through the vulcanization process. By maintaining the uniform cord arrangement of the strips including the seams, the quality of the product tire, especially the separation resistance and pressure resistance of the carcass ply, can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the process of creating a case hand. ■...Band forming drum 2...Case band 3
... Seam pasting sheet 4 ... Seam 5 ... Code

Claims (1)

[Claims] 1. When molding a green case for a pneumatic tire with a radial structure carcass as body reinforcement, rubberized cord strips to be applied to the plies of the carcass are sequentially applied to the case band forming drum according to the type of ply. When the cord strip is wrapped and laminated, a rubber of the same type as the covering rubber of the cord strip is placed on the butt joining joint between the winding start end and the winding end of the cord strip occupying at least the innermost and/or outermost side of the carcass. Stitching is performed after pasting the stitching sheet, which is made up of the following steps: Following the creation of this case band, the green case and green tire are formed, and through the shaping and vulcanization process, including the butt joint seams. A method for forming a band for a carcass of a pneumatic tire, characterized by maintaining a uniform cord arrangement of the strips.