DE102010000050A1 - Steel cord for use as strength carrier in e.g. belt ply of passenger car pneumatic tire, has core filament comprising tensile strength ranging between specific values, and coating filaments comprising strength larger than specific value - Google Patents

Abstract

The cord has an inner layer made from a core filament (1) and coating filaments (2) e.g. ultra high tensile (UHT)-steel filaments. The coating filaments are arranged around the core filament. The core filament comprises a tensile strength ranging between 3200 to 3500 Newton/mm square. The coating filaments comprise a tensile strength larger than 3800 Newton/mm square. A diameter of the coating filaments ranges between 0.15 and 0.25 mm. A diameter of the core filament ranges between 0.19 and 0.25 mm.

Description

The invention relates to a steel cord for use as reinforcement in components of pneumatic vehicle tires, consisting of an inner layer of at least one core filament and at least one layer of enveloping filaments.

The invention further relates to the use of this steel cord as a strength carrier in a rubber layer of a pneumatic vehicle tire.

Multilayer steel cords of different constructions are known in principle. For example, in the EP 0 849 098 B1 Steel cords of various multilayer constructions mentioned, all filaments should have a consistent tensile strength, which should be between 3500 and 4200 N / mm ² . The mentioned steel cords include, for example, the constructions 1 + 2, 1 + 3, 1 + 4, 1 + 5, 1 + 6, 1 + 7, 1 + 8, 2 + 1, 2 + 2, 2 + 5, 2 + 6, 2 + 7, 2 + 8, 2 + 9, 3 + 1, 3 + 2, 3 + 3, but also three-layer constructions.

Steel cord constructions are also known, which consist of filaments whose tensile strength is different from each other. From the U.S. Patent 5,285,623 For example, in the case of a steel cord of construction 2 + 2, for example of the construction 2 × 0.22 mm + 2 × 0.28 mm, it is known that the one pair of filaments has a tensile strength in the so-called normal-tensile range and the second Pair of filaments has a tensile strength so-called in the high-tensile range. The two pairs of filaments are twisted together, so there is no distinction between core filaments and enveloping filaments. A preferred use of this steel cord is as a strength carrier in belt layers of passenger car pneumatic tires.

Among other things, fatigue resistance of the steel cord reinforcements such as those in the carcass ply (s), the bead reinforcements and the belt plies is of great importance for a long life of a pneumatic vehicle tire. If an unsatisfactory fatigue resistance is compensated for by a smaller mutual spacing of the steel cords, this is at the expense of the tire weight. There is therefore a desire to have as fatigue-resistant steel cord available and to be able to reduce the mutual distance of steel cords within the tire component. For truck tires, this is especially important in the carcass deposits.

The invention is therefore based on the object to improve a steel cord in this regard.

The object is achieved according to the invention in that the core filament (or the core filaments) have a tensile strength between 3200 to 3500 N / mm ² and the enveloping filaments have a tensile strength greater than 3800 N / mm ² .

It has been found to be of particular advantage for the fatigue resistance of a multilayer steel cord according to the invention if the core filaments have a tensile strength in the high-tensile range and the encasing filaments have a tensile strength greater than 3800 N / mm ² .

In such exported steel cords, the core filaments are better able to withstand bending loads, which is overall more important for the fatigue resistance of the cord than the enveloping filaments, which have a higher breaking strength. When these steel cords are used as reinforcements in rubber layers of pneumatic vehicle tires, their mutual distance can be made larger than steel cords of the prior art. The greater distance gives the cords more freedom of movement and helps to improve the durability of the tire.

As a result, a strength member is provided which achieves a higher tensile strength, an improved breaking strength and thus an improved durability compared to the strength member of the prior art.

The following tensile strength classes are distinguished: UHT (Ultra High Tensile) 3800-4100 N / mm ² SHT (Super High Tensile) 3500-3800 N / mm ² HT (high-tensiles) 3200-3500 N / mm ² NT (normal tensiles) 2800-3200 N / mm ² .

The multi-layer steel cords may be so-called compact cords in which all layers have the same direction of impact, as well as steel cords in which the direction of impact may vary from layer to layer.

In another embodiment, the enveloping filaments are UHT (Ultra High Tensile) steel filaments having a tensile strength between 3800 and 4100 N / mm ² . It is an improved breaking strength with optimized durability of the strength member achieved.

Preferred cord construction is 1 + 5 or 1 + 6 or 1 + 18. In these constructions, one core filament and five, or 6 or 18 enveloping filaments are arranged around this core filament. A good packing density of the cord is achieved, whereby the breaking strength is increased.

An alternative cord has the construction 3 + 9. This cord has three core filaments and nine enveloping filaments.

In cord constructions where multiple core filaments are present, in one particular embodiment at least one core filament has a tensile strength of between 3200 to 3500 N / mm ² and at least one other core filament has a tensile strength of between 2800 and 3200 N / mm ² . The core filaments of a cord have different tensile strengths. The flexural strength of the cord and its strength are optimized.

It is advantageous if the diameter of the enveloping filaments between 0.15 and 0.25 mm and when the diameter of the core filaments between 0.19 and 0.25 mm. As a result, a comparatively thinner and lighter, but very durable and fatigue-resistant cord is created. The diameters of the core and enveloping filaments may be the same or different within a strength member. With (approximately) equal diameters of core and enveloping filaments, the production of the cord is simplified.

Steel cords designed in accordance with the invention are preferably usable as reinforcements in rubber layers of pneumatic vehicle tires, in particular in a belt ply, a bead reinforcing ply or a carcass ply.

Further features, advantages and details of the invention will now be described with reference to the drawings illustrating embodiments. It show the:

1 a cross section through a steel cord designed according to the invention;

2 a cross section through another steel cord according to the invention;

3 a cross section through another steel cord according to the invention;

4 a cross section through another steel cord according to the invention.

The Indian 1 shown steel cord has the construction 1 + 5 and consists of a core filament 1 , The core filament 1 , which are also referred to as the "soul" of the steel cord, is of five filaments 2 enveloped, which around the core filament 1 are arranged.

All enveloping filaments 2 each have matching diameter, wherein the diameter of the core filament 1 from that of the enveloping filaments 2 can differentiate. The diameter of the core filament 1 is between 0.19 and 0.25 mm, in particular between 0.19 and 0.22 mm. The diameters of the enveloping filaments 2 is between 0.15 and 0.25 mm, preferably between 0.20-0.22. The lay lengths are chosen in the usual range and are between 8 mm and 14 mm.

The fatigue resistance of the steel cord is particularly great when the core filament 1 a tensile strength of between 3200 and 3500 N / mm ² , therefore in the HT (high-tensile) range, in particular of the order of 3300 N / mm ² . The enveloping filaments 2 have a greater tensile strength than the core filament 1 , The tensile strength of the enveloping filaments 2 is greater than or equal to 3800 N / mm ² and is therefore in the UHT (Ultra High Tensile) range.

The 2 shows a cross section through another steel cord according to the invention. The steel cord of the 2 differs from the steel cord of the 1 in that the steel cord of the 2 the construction has 1 + 6, so a Kernfilament 1 and six enveloping filaments 2 having.

The 3 shows a cross section through another steel cord according to the invention. The steel cord of the 3 differs from the steel cord of the 1 in that the steel cord of the 3 the construction has 1 + 18, so a Kernfilament 1 and eighteen enveloping filaments 2 in two layers. (Kompaktkord).

The 4 shows a cross section through another steel cord according to the invention. The steel cord of the 4 differs from the steel cord of the 1 in that the steel cord of the 4 the construction has 3 + 9, so three core filaments 1 and nine enveloping filaments 2 having. The core filaments 1 can have the same or different tensile strength. In one example of equal tensile strengths, the core filaments have 1 a tensile strength in the high-tensile range of 3300 N / mm ² on.

As a result of the fatigue resistance, it is particularly advantageous to use steel cords designed according to the invention in rubber layers of pneumatic vehicle tires, for example in belt layers, bead reinforcements or carcass inserts, for example as reinforcements in carcass inserts of tires for trucks. Examples of concrete constructions for this purpose are:
1 × 0.20 mm (HT) + 18 × 0.175 mm (UHT), lay length 10 mm.
3 × 0.22 mm (HT) + 9 × 0.20 mm (UHT), lay length 12.5 mm.

The mutual distance of such steel cords in the carcass ply of a truck tire may be greater than 0.60 mm, in particular up to 0.80 mm, depending on the tire dimension.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0849098 B1 [0003]
• US 5285623 [0004]

Claims (8)

Steel cord for use as reinforcement in components of pneumatic vehicle tires consisting of an inner layer of at least one core filament and of at least one layer of enveloping filaments, characterized in that the core filament ( 1 ) a tensile strength between 3200 to 3500 N / mm ² and the enveloping filaments ( 2 ) have a tensile strength greater than 3800 N / mm ² . Steel cord according to claim 1, characterized in that the enveloping filaments ( 2 ) Are UHT (Ultra High Tensile) steel filaments and have a tensile strength between 3800 and 4100 N / mm ² . Steel cord according to one of claims 1 to 2, characterized in that it has the construction 1 + 5 or 1 + 6 or 1 + 18. Steel cord according to one of claims 1 to 2, characterized in that it has the construction 3 + 9. Steel cord according to one of claims 1 to 2, 4, characterized in that at least one core filament has a tensile strength between 3200 to 3500 N / mm ² and at least one other core filament has a tensile strength between 2800 and 3200 N / mm ² . Steel cord according to one or more of the preceding claims, characterized in that the diameter of the enveloping filaments is between 0.15 and 0.25 mm and that the diameter of the core filaments is between 0.19 and 0.25 mm. Use of a steel cord according to at least one of claims 1 to 6 as a strength member in a rubber layer of a pneumatic vehicle tire. Use according to claim 7, characterized in that the rubber layer is a belt ply, a bead reinforcement or a carcass ply.

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