GB1563237A

GB1563237A - Bead cores for pneumatic tyres

Info

Publication number: GB1563237A
Application number: GB4186776A
Authority: GB
Original assignee: Continental Gummi Werke AG
Current assignee: Continental AG
Priority date: 1975-10-10
Filing date: 1976-10-08
Publication date: 1980-03-19
Also published as: ATA715276A; DE2545380A1; FR2327110B2; AT351955B; FR2327110A2; IT1077050B

Description

(54) BEAD CORES FOR PNEUMATIC TYRES (71) We, CONTINENTAL GUMMI WERKE AKTIENGESELLSCHAFT of Continental-Haus/Postfach 169, 3000 Hannover, Federal Republic of Germany; a German body corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a bead core for pneumatic tyres produced by compacting an assembly comprising a plurality of coils of filamentary material, desirably in the form of wires or cables.

In our U.K: Patent No. 1498314, there is described and claimed an assembly comprising a plurality of loops of filamentary material in which each loop passes through at least another loop to be interlinked therewith, which loops mechanically interlock when the assembly is compacted to form a bead core for a pneumatic tyre, with each loop extending over the whole circumference of the bead core.

This parent patent makes it possible to provide a special structure of tyre bead core without a self-adhesive bond between the adjacent wire coils whereby as a result of the measures adopted, the complete abandoning of the otherwise necessary coating of the reinforcing members with adhesion-imparting material is possible, and as a consequence thereof savings in effort and manufacturing costs are achieved.

A specific form of solution is aimed at in the parent patent by forming the loops by coils of a single member formed of the filamentary material. In such case, the single member desirably has its ends connected to each other.

The present invention aims at providing a further development of the subject matter of the parent patent with improvements of the structure of the bead cores and in the mutual cohesion of the coils.

According to the present invention, there is provided an assembly, as claimed in claim 3 of U.K. Patent No. 1498314, comprising a bead core for pneumatic tyres produced from a first pair of adjacent coils having a number of circumferential overlaps with each other, and a second pair of adjacent coils having a different number of circumferential overlaps with each other, said numbers differing by at least 2, and in which each coil has an odd number of circumferential overlaps with the other coils.

Depending upon the desired object, the pair of adjacent coils at one end of the bead core may have a greater number of circumferential overlaps with each other than have the pair of adjacent coils with each other at the other end. Alter.natively, the pair of adjacent coils at one end of the core may have a smaller number of circumferential overlaps with each other than have the pair of adjacent coils with each other at the other end.

In another embodiment, the pair of adjacent coils at one end and the pair of adjacent coils at the other end may have a greater number of circumferential overlaps with each other than have adjacent coils with each other located between said pairs of adjacent coils at said one end and said other end.

In a preferred embodiment of the present invention, the difference between the circumferential overlaps of adjacent coils may be a multiple of 2.

The present invention relates to the provision of a particularly favourable bead core utilizing the technical theory stated in the parent patent. Since the differing number of circumferential overlaps in pairs of adjacent coils result in different angles of pitch, such arrangement prevents the undesired phenomenon that the individual coils of the reinforcing member which are wound one onto the other are drawn in random and uncontrolled manner into the spaces of the given inner coil and therewith cause local irregularities in the material distribution and in the cross-sectional structure of the completed bead cores.

The present invention provides the conditions for a core structure homogenous in all parts with an undisturbed course of coils, which in further consequence forms the basis in the qualitative property of the pneumatic tyres fitted with such bead cores.

These advantages are to be estimated the higher as they can be obtained with relatively simple means without the necessity of varying the direction of the winding after the production of a single coil.

Moreover, the invention opens multiple possibilities for mutually grading the frequency of overlap in the individual core coils, in order depending upon the type and design of the pneumatic tyre and the associated bead cores to obtain special effects in the bead structure. It may, for example, prove to be favourable to provide a large number of overlaps in the pair of adjacent coils at one end to ensure a firm base for commencing the winding operation or in the interior of the core cross-section.

On the other hand, it may be more favourable for the cohesion of the whole bead core to select a large number of circumferential overlaps for the pair of adjacent coils at the other end.

The increase or reduction of the overlaps may be effected from one coil to the other in optional stages or steps. Thus, the difference of the number of overlaps of pairs of adjacent coils is at least equal to 2, but may be equal to a multiple thereof.

The invention will be further illustrated, by. way of example, with reference to the accompanying drawing, in which the single Figure shows an exploded schematic view of the coil course of a core ring in accordance with the invention - shown highly simplified for clarity.

The assembly shown in the drawing is built up from interlocking coils 15 of a cutto-length coiled steel wire or the like reinforcing member and subsequently made endless. For reasons of simplification of the drawing and improved clarity, only four coils are shown, whereby the first coil extends from region A to region B, the second coil from B to C, the third coil from C to D and the fourth coil from D to A.

Inasmuch as the individual coils overlap or merge with each other over large circumferential sections and are subject to changes in their location at the intersections until the coils have been finally pushed together and the core ring has been compacted, the start and end cannot be mathematically defined; however, for understanding the invention, only the consideration of the mutual overlapping is of importance.

As illustrated, the first coil (A-B) has eleven overlaps with the other coils atop, j, q, f, a, b, c, d, g, and l; coil B-C has nine overlaps with the other coils at k, q, e, a, b, c, d, h and m; the coil C-D has seven overlaps with the other coils at p, i, e, f g, h, n; and coil D-A has seven overlaps with the other coils at o, i, j, k, 1, m and n.

WHAT WE CLAIM IS:- 1. A bead core for pneumatic tyres produced from an assembly, as claimed in claim 3 of U.K. Patent No. 1498314, comprising a first pair of adjacent coils having a number of circumferential overlaps with each other, and a second pair of adjacent coils having a different number of circumferential overlaps with each other, said numbers differing by at least 2, and in which each coil-has an odd number of circumferential overlaps with the other coils.

2. A bead core as claimed in claim 1, in which the pair of adjacent coils at one end have a larger number of circumferential overlaps with each other than have the pair of adjacent coils with each other at the other end.

3. A bead core as claimed in claim 1, in which the pair of adjacent coils at one end have a smaller number of circumferential overlaps with each other than have the pair of adjacent coils with each other at the other end.

4. A bead core as claimed in claim 1, in which the pair of adjacent coils at one end as well as the pair of adjacent coils at the other end have a greater number of circumferential overlaps than have adjacent coils with each other located between said pairs of adjacent coils at said one and said other ends.

5. A bead core as claimed in any one of claims 1 to 4, in which the difference between circumferential overlaps of adjacent coils is a multiple of 2.

6. A bead core, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. in all parts with an undisturbed course of coils, which in further consequence forms the basis in the qualitative property of the pneumatic tyres fitted with such bead cores. These advantages are to be estimated the higher as they can be obtained with relatively simple means without the necessity of varying the direction of the winding after the production of a single coil. Moreover, the invention opens multiple possibilities for mutually grading the frequency of overlap in the individual core coils, in order depending upon the type and design of the pneumatic tyre and the associated bead cores to obtain special effects in the bead structure. It may, for example, prove to be favourable to provide a large number of overlaps in the pair of adjacent coils at one end to ensure a firm base for commencing the winding operation or in the interior of the core cross-section. On the other hand, it may be more favourable for the cohesion of the whole bead core to select a large number of circumferential overlaps for the pair of adjacent coils at the other end. The increase or reduction of the overlaps may be effected from one coil to the other in optional stages or steps. Thus, the difference of the number of overlaps of pairs of adjacent coils is at least equal to 2, but may be equal to a multiple thereof. The invention will be further illustrated, by. way of example, with reference to the accompanying drawing, in which the single Figure shows an exploded schematic view of the coil course of a core ring in accordance with the invention - shown highly simplified for clarity. The assembly shown in the drawing is built up from interlocking coils 15 of a cutto-length coiled steel wire or the like reinforcing member and subsequently made endless. For reasons of simplification of the drawing and improved clarity, only four coils are shown, whereby the first coil extends from region A to region B, the second coil from B to C, the third coil from C to D and the fourth coil from D to A. Inasmuch as the individual coils overlap or merge with each other over large circumferential sections and are subject to changes in their location at the intersections until the coils have been finally pushed together and the core ring has been compacted, the start and end cannot be mathematically defined; however, for understanding the invention, only the consideration of the mutual overlapping is of importance. As illustrated, the first coil (A-B) has eleven overlaps with the other coils atop, j, q, f, a, b, c, d, g, and l; coil B-C has nine overlaps with the other coils at k, q, e, a, b, c, d, h and m; the coil C-D has seven overlaps with the other coils at p, i, e, f g, h, n; and coil D-A has seven overlaps with the other coils at o, i, j, k, 1, m and n. WHAT WE CLAIM IS:-

1. A bead core for pneumatic tyres produced from an assembly, as claimed in claim 3 of U.K. Patent No. 1498314, comprising a first pair of adjacent coils having a number of circumferential overlaps with each other, and a second pair of adjacent coils having a different number of circumferential overlaps with each other, said numbers differing by at least 2, and in which each coil-has an odd number of circumferential overlaps with the other coils.