EA013332B1 - Hose with the use of high-strength wire of a nonround section with the increased fatigue endurance - Google Patents

Abstract

The invention relates to the field of flexible hoses made of elastomers reinforced with steel wire. The problem solved by the invention is to increase the service life of the hose. The technical result obtained from the use of the invention is in increasing the density of the engagement of wires to each other in the hose and increasing its fatigue endurance. The solution of the problem provided with that the hose with the use of high-strength wire of a nonround section with the increased fatigue endurance comprises at least one flattened wire with plane stresses from plastic deformation of the flattening in the parallel flattening rollers having two flat sides and two rounded edges of a natural shape. According to the invention, the flattened wire has a homogeneous structure with no internal defects such as interstices and compressive stresses from its rounded ends in the range of 0.65 to 0.8 from the ultimate strength of the material destruction, and the hose has the endurance level of more than 3000 cycles in a low-cycle area. The geometrical shape of the rounded end of the wire is described by the formula:R=S/2+h/8S,where R - a curvature radius; S - height of the curvature arc; h - thickness of the flattened wire. The wire in the cross section may have a rounded edge of a radius, elliptical, alternate radius or other shape. The wire edge form can be flattened, which provides a lock joint with the increased density of the engagement of the wires to each other when placing the wire in the spiral winding. The wire can be winded in a shape of spiral or braiding.

Description

The invention relates to the field of flexible hoses of elastomers reinforced with steel wire.

Reinforcement of rubber hoses is caused by the desire to strengthen it to ensure operability at high pressures. The most effective are hoses reinforced with steel wire. At the same time, layer-by-layer spiral winding of a wire on a rubber base is considered the most acceptable.

The main direction in the manufacture of hoses is to reduce the wall thickness of the hose through the use of wire of increased strength or by reducing the diameter of the wires with an increased frequency of winding. In addition, a decrease in wire thickness while maintaining a cross-sectional area led to the appearance of rolled wire as a reinforcing material. The use of rolled wire prevents the destruction of the rubber of the reinforcing layer and located between the layers, which increases the service life of the high-pressure hose. The use of rolled wire in comparison with a round wire with a diameter equal to the thickness of rolled wire makes it possible to increase the pressure inside the sleeve due to its higher strength compared to a round wire.

Known hose using rolled wire for reinforcement [1]. The high-pressure hose has at least two layers reinforced with wires, the wires being laid in contact with each other in the layer. The number of contact points when using rolled wire is less than when using round wires. Due to the fact that the ratio of the thickness of the rolled wire to the width is in the range 1: 5-1: 2, the number of rolled wires in the layer is less than the number of round wires with the same total strength of the reinforcing layer.

As a prototype adopted sleeve high pressure (RVD), reinforced with at least one rolled steel wire [2]. At least one wire is wound in a spiral, forming a spiral WFD. The WFD is reinforced with more than one wire and is bound with several flattened wires. According to the formula, the rolled wire has a natural edge shape. The ratio of thickness to width of the rolled wire is less than 0.95 (1: 1.05). The tensile strength of rolled wire is 3500-2000 / th (d is the diameter of the circle with the same cross-sectional area of rolled wire). Residual elongation at maximum load is at least 0.7%. The tensile strength of ultra-high strength rolled wire exceeds 4300-2000.

Flattened wire is obtained by rolling a round wire between two parallel rolls and has two flat sides and two rounded edges of a natural shape. From the rounded edges of the wire does not undergo any deformation. Flattening of a round steel wire already at a ratio of thickness to width of rolled wire less than 0.95 allows to increase ductility.

The disadvantages of the prototype include the fact that the flattened wire for reinforcing the WFD obtained by the method described above may have internal defects due to the large unevenness of deformation between the outer and inner layers of the wire with a ratio of thickness to width of the rolled wire less than 0.95. The deformation of the inner layers of a round wire under the action of compressive loads from the side of the flat rolls is directed along the axis of the wire in the direction of the lumen between the rolls at a speed greater than the surface layers in contact with the flat rolls. In this case, the difference in the deformations of the round wire can reach a level when cavities are formed in the center of the wire due to the formation of tensile stresses exceeding the strength of the wire material (Fig. 1). The hose reinforced with flattened wire, obtained according to the patent [2], has a low level of cycles when tested for fatigue endurance due to the presence of internal defects (Fig. 2).

The problem solved by the invention is to increase the life of the hose.

The technical result obtained from the use of the invention is to increase the tightness of the wires to each other in the hose and increase its fatigue resistance.

The solution to this problem is provided by the fact that a hose using a high-strength non-circular wire with increased fatigue resistance contains at least one flattened wire with flat stresses from plastic flattening in parallel flattening rolls, having two flat sides and two rounded edges of a natural shape. According to the invention, the rolled wire has a homogeneous structure without internal defects in the form of voids and compressive stresses from its rounded ends in the range of 0.65-0.8 of the temporary resistance to fracture of the material, while the hose has a level of endurance in the low-cycle region for more than 3000 cycles.

The geometric shape of the rounded end of the wire is described by the expression

+ K = 5/2 to ^2/85, where R - radius of curvature;

- the height of the arc of the curve;

- thickness of rolled wire,

- 1 013332

The wire in cross section may have a rounded edge of a radial, elliptical shape, a shape of variable radius or other shape.

The shape of the edge of the wire may have a flattened shape, which ensures that it is locked in a spiral winding when it is laid in a spiral winding, with an increased density of contact of the wires to each other.

The wire can be wound in the form of a spiral or weave. The invention is illustrated by drawings, where in FIG. 4 shows a high pressure hose with a flat wire in the lock. The view of the rolled wire after processing by compressive stresses from the rounded ends is shown in FIG. 3.

The present invention provides a hose reinforced with rolled wire without internal defects in the form of voids. In contrast to the prototype, flattened wire during flattening deformation experiences not only plane stresses from parallel flattening rolls, leading to plastic flow of the wire, but also compressive stresses from the rounded ends in the range of 0.65-0.8 of the temporary fracture resistance of the material. The cross-sectioned wire thus obtained may have a rounded edge of a radial, elliptical shape (variable radius shape) or another shape. The wire does not have voids in the cross section resulting from elastic tensile stresses. In addition, the shape of the edge of the wire may have a flattened appearance. When laying such a wire in a spiral winding in a hose, a lock connection is created, while the adherence of the wires to each other increases, which prevents the destruction of rubber under the action of internal pressure (Fig. 4). Designations of the geometrical parameters of the rolled wire are shown in FIG. 6.

An example of a specific use.

The table shows the comparative characteristics of flattened wire obtained in various ways: flattening between two parallel rolls and using compressive stresses from the rounded ends in the range of 0.65-0.8 of the temporary resistance to fracture of the material.

The number of twists was estimated at a length of samples equal to 100 x the width of the wire. The number of bends was determined during bending through a mandrel with a radius of jaws of 2.5 mm. The endurance level was found when testing with a 3-roller test (Fig. 5), in which the wire sample was subjected to alternating bending in three rollers with an additional tensile load (P) in the low-cycle test area. The distance between the rollers is 28.5 mm, the diameter of the rollers is 22.0 mm. The tensile load was set equal to 10% of the breaking strength of the wire.

Comparative characteristics of flattened wire obtained in various ways

The method of obtaining wire Wire sizes, mm Breaking Strength, N Number of twists Number of bends Endurance, number of cycles width on height according to patent Ψ02005108846 0.60 0.30 477 27 78 2024 With compressive stresses on the sides 0.60 0.30 468 27 88 3516

The data presented in the table show a clear advantage in the number of bends and endurance of rolled wire using compressive stresses from the rounded ends in the range of 0.65-0.8 of the temporary resistance to fracture of the material.

Thus, the hose (high pressure sleeve) reinforced with rolled wire using compressive stresses from the rounded ends in the range of 0.65-0.8 of the temporary resistance to fracture of the material will also have a higher level of endurance in comparison with the prototype.

Information sources

1. Patent OB 1239884. Improvements regarding rubber hoses of high pressure. 07/21/1971

2. Patent XVO 2005108846. Flat high-strength wire as a hose reinforcer. November 17, 2005 (prototype).

Claims (9)

CLAIM 1. A hose using high-strength non-circular wire with increased fatigue resistance, including at least one flattened wire with flat stresses from plastic deformation of flattening in parallel flattening rolls, having two flat sides and two rounded edges of a natural shape, characterized in that the flattened wire has a homogeneous structure without internal defects in the form of voids and compressive stresses from its rounded ends in the range of 0.65-0.8 of the temporary resistance destruction of the material, while the hose has a level of endurance in the low-cycle region for more than 3000 cycles, and the geometric shape of the rounded end of the wire is described by the expression where K is the radius of curvature; 8 - the height of the rounding arc; E is the thickness of the rolled wire. 2. The hose according to claim 1, characterized in that the rolled wire in cross section has a rounded edge of a radius, elliptical shape, a shape of a variable radius or other shape. 3. The hose according to claim 1, characterized in that the shape of the edge of the wire has a flattened shape, which ensures that when laying it in a spiral winding, a lock connection with an increased density of contact of the wires to each other. 4. The hose according to claim 1, characterized in that the rolled wire is wound in the form of a spiral. 5. The hose according to claim 1, characterized in that the rolled wire is wound in the form of weaving. 6. The hose according to claim 2, characterized in that the rolled wire is wound in the form of a spiral. 7. The hose according to claim 2, characterized in that the rolled wire is wound in the form of weaving. 8. The hose according to claim 3, characterized in that the rolled wire is wound in the form of a spiral. 9. The hose according to claim 3, characterized in that the rolled wire is wound in the form of weaving. Type of rolled wire with inner void