Belt comprising steel cords adapted for wear detection
A belt containing steel cords, the steel cords containing strands made of steel filaments wherein the largest diameter filaments are at least intermittently positioned at the radially outer side of the steel cord. Such a configuration can be obtained by using steel cord constructions wherein the thickest filaments are positioned outside of the steel cord which is contrary to the current practice. In a further embodiment the largest diameter filaments fill up some or all of the valleys of the strands at their radially outer side. These monofilaments thus have the same lay length and direction as the strands in the steel cord. The advantage of putting the largest filaments at the outside is that they will break first and thus will be readily detectable by electrical, magnetic or visual means. In this way a belt is provided that can be monitored easier and more conveniently than prior art belts.
1. A belt comprising steel cords held in parallel arrangement to one another by an elastomer jacket, said steel cords comprising strands twisted together with a cord lay direction and cord lay length, wherein said strands comprise steel filaments twisted together, each of said steel filaments having a filament diameter,
wherein
in each steel cord, a group of largest diameter filaments have a filament diameter that is strictly larger than the diameters of the remainder of the filaments, and wherein each of said largest diameter filaments is at least intermittently present at a radial outer side of any one of said steel cords, and
wherein the cross sectional area of each one of the filaments out of the group of largest diameter steel filaments is between 2% and 10% of the total cross sectional area of any one of said steel cords.
2. The belt according to claim 1 wherein the group of largest diameter filaments are made of steel having a relative magnetic permeability larger than 50 and wherein at least said largest diameter filaments are configured to have a remnant magnetisation.
3. The belt according to claim 1 wherein the largest diameter filaments differ in diameter by at least 1% and at most 40% with relative to the next smaller diameter steel filaments.
4. A belt comprising steel cords held in parallel arrangement to one another by an elastomer jacket, said steel cords comprising strands twisted together with a cord lay direction and cord lay length, wherein said strands comprise steel filaments twisted together, each of said steel filaments having a filament diameter,
wherein
in each steel cord, a group of largest diameter filaments have a filament diameter that is strictly larger than the diameters of the remainder of the filaments, and wherein each of said largest diameter filaments is at least intermittently present at a radial outer side of any one of said steel cords and,
wherein in any one of said steel cords, the filaments of the group of the largest diameter filaments are monofilaments made of metal, said monofilaments being twisted with said cord lay length and direction, said monofilaments filling some or all of the valleys between adjacent strands on the radial outer side of said steel cord, wherein the diameter of said monofilaments is larger than a gap between said adjacent strands.
5. The belt according to claim 4 wherein said monofilaments are configured to remain within a circumscribed circle of the strands of said steel cords.
6. The belt according to claim 4 wherein said monofilaments have a monofilament tensile strength, said monofilament tensile strength being lower than the tensile strength of any other of said steel filaments in the strands of any one of said steel cords.
7. The belt according to claim 4 wherein said monofilaments of any one of said steel cords have a total monofilament breaking load, said total monofilament breaking load being lower than 20% of the breaking load of each steel cord.
8. The belt according to claim 4 wherein at least one of said monofilaments of at least one of said steel cords is coated with an electrically insulating layer.
9. The belt according to claim 4 wherein at least one of said monofilaments of at least one of said steel cords is locally weakened at intervals.
10. A belt comprising steel cords held in parallel arrangement to one another by an elastomer jacket, said steel cords comprising strands twisted together with a cord lay direction and cord lay length, wherein said strands comprise steel filaments twisted together, each of said steel filaments having a filament diameter,
wherein
in each steel cord, a group of largest diameter filaments have a filament diameter that is strictly larger than the diameters of the remainder of the filaments, and wherein each of said largest diameter filaments is at least intermittently present at a radial outer side of any one of said steel cords,
wherein said steel cords further comprise a core, said strands being twisted around said core, and wherein a number of the strands in said steel cords is three, four or five.
11. The belt according to claim 10 wherein said core of said steel cords comprises steel filaments forming a core strand, said core strand has a core strand diameter, wherein said core strand diameter is smaller than said strand diameter.
12. A belt comprising steel cords held in parallel arrangement to one another by an elastomer jacket, said steel cords comprising strands twisted together with a cord lay direction and cord lay length, wherein said strands comprise steel filaments twisted together, each of said steel filaments having a filament diameter,
wherein
in each steel cord, a group of largest diameter filaments have a filament diameter that is strictly larger than the diameters of the remainder of the filaments, and wherein each of said largest diameter filaments is at least intermittently present at a radial outer side of any one of said steel cords, and
wherein a closest distance between a surface of said belt and any one of said steel cords is larger than half the filament diameter of said group of largest diameter filaments and smaller than ten times the filament diameter of said group of largest diameter filaments.