IE56076B1 - Solid tyre - Google Patents

Abstract

1. Solid tyre, which is formed from rubber or rubber-like substances and constructed from one or a plurality of layers, and wherein fibres are inserted in at least the lower layer, characterised in that the fibres (5) have a length of 1 to 5 mm and are chemically bonded to the rubber surrounding them by means of an adhesive system which is added to the rubber mixture for the solid tyre, and in that the fibres (5) preferably extend in the circumferential direction.

Description

The invention relates to a solid tyre to the type which is formed from rubber or rubber like substances and constructed from one or a plurality of layers, and wherein fibres are inserted in at least the lower layer.

It is known that the addition of fibres into rubber mixtures makes the manufacture of solid tyres more economical, and the thus obtained vulcanised product is compacted. Thereby, the fibres are added to the solid tyre in different layers, depending on the area of application. With such solid tyres, comprising a rubber-tread strip, a resilient rubber pad and a base ring of tough rubber, it is particularly important to provide an extremely tough mixture for the base-ring rubber including its embracing steel-wire inserts, so that, for example, the tyre, which is pressure mounted onto a cylindrical surface of the rim, maintains its secure mounting position even under severe loads. For all types of solid tyres, suitable materials for fibres to be added are, for example, mineral fibres such as asbestos, synthetic fibres such as rayon, nylon, PE and others, animal fibres such as wool, and vegetable fibres such as wood. Metal, glass and carbon can also be suitable.

Known solid tyres with fibrous particles and inserted into the base-ring rubber have shown that the fibrous particles are active within the rubber mixture due to the constantly changing load conditions whilst operative, thereby damaging the surrounding rubber due to these internal movements, resulting in the rubber often becoming brittle after a short time, thus endangering the fit of the tyre to the rim body. β It is therefore, the object of the invention to disclose a solid tyre wherein damage to the rubber due to activity of the inserted fibrous particles is prevented, thus guaranteeing safe fitting onto the rim and reliable operation.

This object is achieved/ according to the invention by the characterising features of patent claim 1.

Thereby, the adhesive system is added directly to the rubber mixture. Due to chemical bonding of the fibre surface and the adjacent rubber, the finished tyre no longer contains loose foreign bodies within the rubber, so that no sawing effects can occur by way of inner movements, but a solidly bonded unit with the rubber is created instead.

By way of the invention, tough rubber mixtures of sofar unattainable quality for the base rings are obtained in an advantageous way, thus giving solid tyres produced in said manner a considerably longer lifespan.

According to one embodiment of the invention, the usual steelwire cores in the base rubber can be totally dispensed with, if fibres with a weight proportion of at least 5% of the basering weight are added at least in the base-ring-rubber layer, and if the thickness of the base-ring-rubber layer is between 10 to 90% of the cross-sectional height of the tyre.

This embodiment is based on the realisation that the embedding of fibres in the base ring at a weight proportion of more than % and the maintaining of a minimum layer thickness for the base ring, which depends on the required operational load of the tyre, achieves a compactness which is so good that the heavy and expensive steel-wire cores can be dispensed with entirely. For achieving a reliable rim mount, the tyre in its assembled state should have an expansion of the inside diameter by 0.5% to 10% relative to the non-assembled state in order to achieve reliable rim mounting.

Apart from a considerable weight reduction due to the abolition of the steel-wire cores, the inventive tyre mainly offers the advantage of simpler and cheaper manufacture (claim ΌA further advantage lies in the considerable reduction in resistance to rolling due to increased rigidity.

Furthermore, by embedding fibres into the resilient rubber pad, this invention is capable of improving the stability of certain vehicles with solid tyres.

Technical advantages can be obtained by this invention even in conjunction with solid tyres with only one rubber layer or with two different rubber layers.

Advantageous embodiments of the invention are contained in the subclaims.

Below, two examples of embodiment of the invention are described and explained, based upon a drawing.

Shown is, in Fig. Is a solid tyre in radial partial cross-section; Fig. 2: a partial top view of a circumferential surface at the height of line II-II; Fig. 3: another solid tyre in radial partial cross-section.

The solid tyre of rubber or rubber-like materials substantially consists of three layers, i.e. a low-wear rubber-tread strip I, a resilient rubber pad 2 and a base ring of tough rubber with steel-wire cores 4 embedded therein.

Fibres 5, which are chemically bonded to the adjacent rubber by means of an adhesive system, for example the known resorcin/hexa system are inserted into the rubber of foot ring 3, and, in the present example, also of the resilient rubber pad 2. The chemical bonding in schematically indicated in the drawing by dots in the immediate vicinity of fibres 5.

The solid tyre of Fig.3 differs from that in Fig.l in that base ring 3 is broadened by approximately one half the crosssectional height of the tyre, that it lacks steel-wire cores, and that the bondingly embedded fibres are located exclusively in base ring 3. If required, these can, of course, also be present in the other two layers. Different proportions of thickness between 10 and 90% of the cross-sectional height of the tyre for base ring 3 are also possible, depending on the individual application of the tyre.

The weight proportion of the fibrous material 5 relative to the total weight of base ring 3 should be at least 5%. Proportions of 15% to 20% have proved to be favourable.

The addition of conventional steel-wire cores is no longer required for a solid tyre with the aforesaid properties, without the safety relative to dismounting from the rim being neglected. The tyre is assembled on a not illustrated rim by means of pressure mounting, whereby the inside diameter of the tyre is expanded by approximately 5% relative to its non30 assembled state in order to produce pre-stressing to ensure secure mounting. No further fixing means are required to ensure secure mounting of the tyre onto the rim.

Synthetic fibrous material, for example a mixture of rayon and nylon, is preferred for fibres 5. It is particularly advantageous to obtain fibres 5 either from waste from the manufacture of corded tyre plies or from the cord plies of old tyres.

The fibres 5 should have a length of 1 to 5 mm, and the ratio length to diameter should be in excess of 20.

The reduced fibres 5, as well as the materials for the appertaining adhesive system, are added to the rubber mixture prior to calendering, thus orientating the initially unsortedly supplied fibrous parts 5 preferably in the direction of movement of the rollers during the calendering process. This results in the fibrous parts 5 being preferably arranged in the circumferential direction during the manufacture of the solid tyre, thus achieving particular high compacting in base ring 3. it must be mentioned that the fibrous parts 5 can also be of metallic material if so required, so that for example brasscoated steel wires of old inflatable tyres can be used. In this case, a known adhesive system for brass or steel respectively will have to be applied.

Fibres of other materials can also be taken into consideration, whereby it is always important that an adhesive system, which ensures a solid chemical bond of the chosen fibre material and the adjacent rubber, is added to the respective rubber mixture.

The aforesaid insertion of fibre material into the resilient rubber pad 2 has proved particularly successful with solid tyres which are provided for fork lifts of great stacking heights. In such cases, the stability of the vehicles is considerably improved by embedding fibre parts 5 into rubber pad 2.

Claims (12)

Claims

1. Solid tyre, which is formed from rubber or rubber-like substances and constructed from one or a plurality of layers, and wherein fibres are inserted in at least the radially 5 innermost layer, characterised in that the fibres have a length of 1 to 5 mm and are chemically bonded to the rubber surrounding them by means of an adhesive system which is added to the rubber mixture for the solid tyre, and in that the fibres preferably extend in the circumferential direction. 10

2. Solid tyre according to claim 1, comprising a low-wear rubber-tread strip, a resilient rubber pad and a base ring formed from tough rubber and comprising steel wire or steel band cores which are embedded therein and extend in the circumferential direction, characterised in that fibres which 15 have been chemically bonded by means of an adhesive system, are inserted in the base ring rubber and in the resilient rubber pad.

3. Solid tyre according to claims 1 or 2, characterised by a resorcinol-hexamethylene tetramine system being used as the 20 adhesive system.

4. Solid tyre according to claim 1, characterised by fibres with a ratio of length/diameter of at least 20.

5. Solid tyre according to claim 1, characterised by fibres formed from synthetic material, more especially from rayon 25 and/or nylon.

6. Solid tyre according to claim 1, characterised by metallic fibres.

7. Solid tyre according to claim 2, characterised in that fibres with a weight proportion of at least 5% of the weight 30 of the base ring are inserted in at least the base-ring-rubber layer, in that the layer thickness of the base-ring rubber is 10 to 90% of the cross-sectional height of the tyre, and in that the adhesively embedded fibres replace conventional, circumferential, metal insert plies such as steel wire cores. 5

8. Solid tyre according to claim 7, characterised in that the fibres in the base ring amount to 15 to 20% of the base ring weight.

9. Solid tyre according to claim 7, characterised in that the layer thickness of the base ring rubber is substantially 10. 50% of the cross-sectional height of the tyre.

10. Solid tyre according to claim 7, characterised in that the tyre has a 0.5 to 10% expansion of the internal diameter to achieve a pre-stressing action in the assembled state.

11. Solid tyre according to claim 10, characterised in that 15 the expansion of the internal diameter in the assembled state is substantially 5% compared with the non-assembled state.

12. A solid tyre substantially as hereinbefore described with reference to the drawings.