Elongated zinc-coated steel wire for elastic card clothing

Abstract

The present invention provides an elongated steel wire comprising a steel filament and a zinc coating layer covering the steel filament, the tensile strength of the elongated steel wire being greater than 2200 MPa, and the elongated steel wire having bending properties of at least 25 bends. Provided is a steel wire having improved bending properties.

Description

Technical Field

[0001] The present invention relates to an elongated zinc-coated steel wire for flexible card clothing. Background Art

[0002] In the production of textiles, the fibers should be arranged in a uniform state, i.e., uniform density and uniform thickness, and impurities should be removed. This is the so-called carding process by flexible card clothing.

[0003] Flexible card clothing, i.e., flexible needle rows, includes small needles provided in a flexible multi-layer fabric substrate. The small needles are made of steel wire bent into a U shape and having a knee. In the carding process, the needles of the flexible card clothing bend when subjected to a load and return to their original position when the load disappears.

[0004] The steel wire for making the flexible card clothing is coated with a zinc coating for corrosion resistance. In the case where the steel needle is corroded, the strength of the steel needle will be reduced due to iron oxide on the surface of the steel needle, making the steel needle weaker and thus unable to provide sufficient carding strength, which may lead to the failure of the needle during the carding process.

[0005] It is also required that the steel wire has high tensile strength and high bending properties to extend the life of the flexible card clothing. Especially during the manufacture of the flexible card clothing and the carding process, high bending properties are beneficial to reducing the risk of wire breakage.

[0006] Generally, the steel wire for flexible card clothing is oil-quenched and tempered steel wire. The oil-quenched and tempered steel wire has a tempered martensite microstructure. For the oil-quenched and tempered steel wire, the wire drawing process and the oil quenching and tempering process precede the zinc coating process, so that the final steel wire has a dull and rough surface, which may cause fiber retention problems of the flexible card clothing. The fiber retention problems lead to poor carding process performance. And if the tensile strength of the oil-quenched and tempered steel wire is higher than 2000 MPa, it becomes relatively more brittle during the zinc coating process, thus increasing the risk of wire breakage, while the bending property of the steel wire is only acceptable.

[0007] Chinese standard YBT056 / 94 discloses a zinc-coated oil-quenched and tempered steel wire for carding. For the zinc-coated oil-quenched and tempered steel wire disclosed in this standard, in the case of round steel wire, the tensile strength is not more than 2060 MPa, or in the case of shaped steel wire, the tensile strength is not more than 2210 MPa.

[0008] There is still a need to develop a steel wire with excellent properties for flexible card clothing. Summary of the Invention

[0009] The object of the present invention is to provide a high-performance elongated steel wire for flexible card clothing.

[0010] Another object of the present invention is to provide an elongated steel wire having high tensile strength and good bending properties.

[0011] According to an aspect of the present invention, there is provided an elongated steel wire comprising a steel monofilament and a zinc coating covering the steel monofilament, the tensile strength of the elongated steel wire being greater than 2200 MPa, and the elongated steel wire having a bending property of at least 25 bends.

[0012] The present invention provides an elongated steel wire having high tensile strength, high corrosion resistance and improved bending properties. This is beneficial to the service life of the elastic card clothing.

[0013] Preferably, the elongated steel wire has a bending property of at least 30 bends. More preferably, the elongated steel wire has a bending property of 35 to 55 bends.

[0014] According to the present invention, the elongated steel wire has a drawn sorbite metal microstructure. This means that the elongated steel wire is a cold-drawn steel wire without oil quenching and tempering treatment. To manufacture the elongated steel wire, the zinc electroplating process is carried out between the wire drawing steps, i.e., the final wire drawing step for achieving the target tensile strength through a series of wire drawing dies is after the zinc electroplating process. The surface of the elongated steel wire is bright and smooth, which reduces the fiber retention problem of the elastic card clothing. And, during the zinc electroplating process, the tensile strength of the steel monofilament is not very high, thereby reducing the concentration of residual stress, reducing the hydrogen embrittlement of the steel monofilament, thus reducing the brittleness problem of the steel wire and improving the bending property of the steel wire.

[0015] The "elongated" steel wire refers to a thin and long steel wire. The diameter of the elongated steel wire is less than 1.5 mm. Preferably, the diameter of the elongated steel wire is less than 0.5 mm, and preferably the diameter is not less than 0.15 mm.

[0016] The elongated steel wire is a single steel wire, and the "steel monofilament" according to the present invention is a bare steel monofilament without any coating, i.e., the steel substrate.

[0017] Preferably, the straightness of the elongated steel wire is not greater than 80 mm / lm. More preferably, the straightness of the elongated steel wire is not greater than 70 mm / lm. Most preferably, the straightness of the elongated steel wire is 5 to 60 mm / lm. With the improved straightness, during the production of the elastic card clothing, the needles made of the elongated steel wire are easily and precisely embedded into the fabric substrate.

[0018] Preferably, the tensile strength of the elongated steel wire is greater than 2300 MPa, preferably the tensile strength is not greater than 3200 Mpa, such as 2600 - 3000 MPa.

[0019] The zinc coating of the elongated steel wire is a thin coating, and its thickness does not exceed 10 μm. Preferably, the thickness of the zinc coating of the elongated steel wire is not greater than 6 μm.

[0020] The slender steel wire can be any type of existing steel wire used for elastic card clothing. The cross-section of the slender steel wire is circular, biconvex, oval, triangular, egg-shaped, rhombic or flat.

[0021] According to the present invention, a method for manufacturing a slender steel wire is provided. The method comprises the following steps:

[0022] a) Providing a slender steel wire comprising a steel monofilament and a zinc coating covering the steel monofilament, the tensile strength of the slender steel wire being greater than 2200 Mpa;

[0023] b) Subjecting the slender steel wire to a heat treatment, the heat treatment comprising first heating for 10 to 20 seconds at a first predetermined temperature of 100 to 300 °C, wherein the first heating rate from ambient temperature to the first predetermined temperature is 1 to 3 seconds, and second heating for 30 to 40 seconds at a second predetermined temperature of 250 to 400 °C, wherein the second heating rate from ambient temperature to the second predetermined temperature is 1 to 3 seconds.

[0024] Preferably, step a) comprises the sub-steps of:

[0025] a1) Straightening the slender steel wire by means of a plurality of straightening machines including at least one spiral straightening machine.

[0026] By using straightening machines, in particular spiral straightening machines, the slender steel wire has better straightness.

[0027] The heat treatment in step b) improves the bending properties of the slender steel wire while maintaining the straightness of the slender steel wire.

[0028] The slender steel wire is used for textiles, such as elastic card clothing. Description of the Drawings

[0029] Figure 1 The measurement of the straightness of the steel wire is described. Detailed Description of the Invention

[0030] The slender steel wire can be manufactured from wire rod.

[0031] First, the wire rod is cleaned by mechanical descaling and / or by chemical pickling in H 2 SO 4 or HCl solution to remove the oxides present on the surface. Then the wire rod is rinsed in water and dried. Then the dried wire rod is subjected to a first series of dry drawing operations to reduce the diameter until a first intermediate diameter.

[0032] At this first intermediate diameter d1, for example, between approximately 2.30 and 3.50 mm, a first intermediate heat treatment is carried out on the dry-drawn steel monofilament, called patenting. Patenting means first austenitizing up to a temperature of about 1000 °C and then carrying out the phase transformation from austenite to pearlite at a temperature of about 580 to 650 °C. Then, the steel monofilament is ready for further mechanical deformation.

[0033] Thereafter, in a second number of diameter reduction steps, the steel monofilament is further drawn from the first intermediate diameter d1 until a second intermediate diameter d2. The second diameter d2 is typically in the range of 1.0 mm to 2.00 mm.

[0034] If the total reduction in the first dry drawing step and the second dry drawing step is not too large, the wire can be directly drawn until the diameter d2.

[0035] At this second intermediate diameter d2, the steel monofilament undergoes a second patenting treatment, i.e., it is austenitized again at a temperature of about 900 to 1000 °C and then quenched at a temperature of 500 to 600 °C to allow transformation to sorbite.

[0036] Then the steel monofilament is galvanized, thereby applying a zinc coating layer with a thickness not greater than 10 μm, or even not greater than 6 μm, on the steel monofilament.

[0037] The final drawing step is performed on the zinc-coated steel monofilament to obtain a final diameter d3 and a final tensile strength. The final diameter d3 is generally less than 1.50 mm, or even less than 0.50 mm. The final tensile strength is greater than 2200 MPa, or even greater than 2300 MPa. Thus, an elongated steel wire is obtained, and it has a metallic microstructure of drawn sorbite. The steel monofilament is a carbon steel monofilament. The carbon content of the steel monofilament is preferably higher than 0.20% by weight, more preferably in the range of 0.50% to 1.2%, and most preferably in the range of 0.6% to 1.1%. The higher the carbon content, the higher the tensile strength. In addition to the carbon content, the steel monofilament includes one or more other elements, such as silicon, preferably in the range of 0.10% to 2.5%, more preferably in the range of 0.15 to 1.60%; manganese, preferably in the range of 0.10% to 2.0%, more preferably in the range of 0.50 to 0.90%; chromium, preferably in the range of 0.0% to 2.0%, more preferably in the range of 0.10% to 1.50%; vanadium, preferably in the range of 0.0% to 2.0%, more preferably in the range of 0.05% to 0.60%; tungsten, preferably in the range of 0.0% to 1.5%, more preferably in the range of 0.1% to 0.70%. The balance is iron and unavoidable impurities. In addition to the above elements, other common elements known in the art may also be included in the steel composition. The above contents are calculated by weight. Optionally, the elongated steel wire is drawn and rolled into a non-circular shape, such as a flat shape, a diamond shape, a double convex shape, a triangular shape, an oval shape, an egg shape, etc., and the equivalent diameter of the non-circular steel wire is less than 1.50 mm, or even less than 0.5 mm. In this case, the equivalent diameter of the non-circular steel wire is considered to be the diameter of the elongated steel wire. The elongated steel wire is straightened by a plurality of straightening machines, such as a spiral straightening machine and a plurality of ordinary straightening machines, thus improving the flatness of the steel monofilament.

[0038] Then, the elongated steel wire is heat-treated to improve the bending performance, including first heating at a first predetermined temperature of 100 to 300 °C for 10 to 20 seconds, wherein the first heating rate from the ambient temperature (i.e., not exceeding 45 °C, such as -10 °C to 45 °C) to the first predetermined temperature is 1 to 3 seconds, and second heating at a second predetermined temperature of 250 to 400 °C for 30 to 40 seconds, wherein the second heating rate from the ambient temperature (i.e., not exceeding 45 °C, such as -10 °C to 45 °C) to the second predetermined temperature is 1 to 3 seconds. The heating rate cannot be very high, otherwise the zinc coating layer will be damaged. The specific heat treatment improves the bending performance of the steel monofilament. The first heating and the second heating are two independent heating processes. The flatness of the elongated steel wire is maintained.

[0039] Table 1 summarizes the comparison data.

[0040] Table 1

[0041]

[0042] Obviously, the steel wire of the present invention has better bending performance and straightness.

[0043] The bending performance is measured according to Chinese standard GB / T238-2002. The tensile strength is measured according to GBT228.1-2021.

[0044] Figure 1 The principle for measuring the straightness of the steel wire is shown as follows: First, take a steel wire about 1.1 m long; Second, fix one end A of the steel wire and let the steel wire hang naturally, and set a reference point C at a vertical distance of 1 m from the end A; Third, measure the horizontal distance from C to the steel wire, and this horizontal distance represents the straightness of the steel wire in mm / lm. Ensure that the other end B of the steel wire is fixed during the measurement process.

Claims

1. An elongated steel wire, the elongated steel wire comprising a steel monofilament and a zinc coating covering the steel monofilament, the tensile strength of the elongated steel wire being greater than 2200 MPa, wherein, the elongated steel wire has a bending property of at least 25 bends.

2. The elongated steel wire according to claim 1, wherein, the elongated steel wire has a bending property of at least 30 bends.

3. The elongated steel wire according to claim 2, wherein, the elongated steel wire has a bending property of 35 to 55 bends.

4. The elongated steel wire according to any one of claims 1 to 3, wherein, the elongated steel wire has a metallic microstructure of drawn sorbite.

5. The elongated steel wire according to any one of claims 1 to 4, wherein, the diameter of the elongated steel wire is less than 1.5 mm.

6. The elongated steel wire according to claim 5, wherein, the diameter of the elongated steel wire is less than 0.5 mm.

7. The elongated steel wire according to any one of claims 1 to 6, wherein, the straightness of the elongated steel wire is not greater than 80 mm / lm.

8. The elongated steel wire according to claim 7, wherein, the straightness of the elongated steel wire is not greater than 70 mm / lm.

9. The elongated steel wire according to claim 8, wherein, the straightness of the elongated steel wire ranges from 5 mm / lm to 60 mm / lm.

10. The elongated steel wire according to any one of claims 1 to 9, wherein, the tensile strength of the elongated steel wire is greater than 2300 MPa.

11. The elongated steel wire according to any one of claims 1 to 10, wherein, the thickness of the zinc coating of the elongated steel wire is not greater than 10 μm.

12. The elongated steel wire according to claim 11, wherein, the thickness of the zinc coating of the elongated steel wire is not greater than 6 μm.

13. The elongated steel wire according to any one of claims 1 to 12, wherein, the cross-section of the elongated steel wire is circular, biconvex, oval, triangular, egg-shaped, rhombic or flat.

14. A method for manufacturing an elongated steel wire according to any one of claims 1 - 13, comprising the following steps: a) providing an elongated steel wire comprising a steel monofilament and a zinc coating covering the steel monofilament, the tensile strength of the elongated steel wire being greater than 2200 MPa; b) subjecting the elongated steel wire to a heat treatment, the heat treatment comprising first heating at a first predetermined temperature of 100 to 300 °C for 10 to 20 seconds, wherein the first heating rate from ambient temperature to the first predetermined temperature is 1 to 3 seconds, and second heating at a second predetermined temperature of 250 to 400 °C for 30 to 40 seconds, wherein the second heating rate from ambient temperature to the second predetermined temperature is 1 to 3 seconds.

15. The method according to claim 15, wherein, step a) comprises sub-steps: a1) straightening the elongated steel wire by a plurality of straightening machines including at least one spiral straightening machine.

16. An elongated steel wire according to any one of claims 1 - 13, the elongated steel wire being for elastic card clothing.

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