Steel wire and manufacturing processes for such materials.

Abstract

DEPCT65 This invention reveals steel wire and the manufacturing processes for such steel wire, including: A wire of steel is defined as being centrally located and having a diameter d; and a layer of steel wire. An M-shaped sheath is arranged around a central steel wire, which is in contact with the steel wire and has... Diameter d1, at least two gaps L are present between the steel wires in the sheath layer M, where M is 4;d,d1, and L satisfy the following relationship: 0.420 < (d / d1) < 0.800, d1 is between 0.20 mm and 0.44. mm, and L greater than or equal to 0.0008 mm, the steel wire of this invention may allow the rubber to fully penetrate into The gap, by its purpose, reduces the amount of air in the steel wire, thus avoiding contact friction. The layer of steel wire failed due to insufficient rubber penetration, which led to further failure. The load-bearing capacity of the steel wire is affected by abrasion, moisture, and similar substances that are flooded from... The location of cracks in the tire surface that penetrate the steel strands will be protected from being flooded. It is inserted into the internal cavities of the hollow steel wire, thereby improving its wear resistance. It resists degradation and impact of tire wear, extending tire lifespan. -----------------------------------------------------------

Description

A steel cord and its preparation process Technical Field

[0001] The invention belongs to the field of steel cords for radial tires, and particularly relates to a steel cord and a preparation process thereof. Background Art

[0002] The key step in improving radial tire performance during tire manufacturing is the tire-forming process of steel cord and rubber. Ideally, the rubber should penetrate the interior of the steel cord, completely covering each individual wire. If the interior of the steel cord remains hollow, moisture that penetrates through external injuries on the tire surface can penetrate into the hollow interior of the steel cord, corroding the cord from within. This deteriorates the fatigue performance of the steel cord and shortens the tire's lifespan. Therefore, the rubber penetration performance of steel cords has become a key indicator in steel cord structural design.

[0003] Currently, the steel cords used in radial tires have a 4×1 structure, but none of them can achieve effective rubber penetration. For example, the F portion in FIG5a is an internal cavity caused by the inability of rubber to penetrate.

[0004] Summary of the Invention

[0005] In view of the above problems, the present invention proposes a steel cord having improved adhesive penetration ability and a stable structure and a preparation process thereof.

[0006] To achieve the above technical objectives and effects, the present invention is implemented through the following technical solutions:

[0007] A steel cord comprising

[0008] A core wire in the center with a diameter of d.

[0009] M sheath steel wires are arranged around the central core steel wire and are tangent to the core steel wire, each having a diameter of d1, and at least two gaps L between the M sheath steel wires; wherein M is 4;

[0010] The d, d1 and L satisfy the following relationship:

[0011] 0.420<(d / d1)<0.800

[0012] d1 is between 0.20mm and 0.44mm

[0013] L≥0.0008mm.

[0014] Preferably, d, d1 and L satisfy the following relationship:

[0015] 0.462<(d / d1)<0.640

[0016] L≥0.006mm.

[0017] Furthermore, in a first preferred embodiment of the present invention, d1 is between 0.20 mm and 0.30 mm, and 0.521<(d / d1)<0.640.

[0018] Furthermore, correspondingly, the L is ≥ 0.015 mm.

[0019] Furthermore, in a second preferred embodiment of the present invention, d1 is between 0.30 mm and 0.44 mm, and 0.462 < (d / d1) < 0.640.

[0020] Furthermore, correspondingly, the L is ≥ 0.010 mm.

[0021] As a further improvement of the present invention, the twist pitch of the M sheath layer steel wires is 5-25 mm, and the twist direction is S or Z direction.

[0022] The present invention also provides a method for preparing a steel cord having the above-mentioned structure, characterized in that: during the twisting process, the one core steel wire and the M sheath steel wires are paid out simultaneously, the pay-out tension of each sheath steel wire is equal, the pay-out tension of the one core steel wire is greater than the pay-out tension of each sheath steel wire, the one core steel wire is placed in a central position, and the M sheath steel wires are evenly distributed 360° around the one core steel wire and bundled together for twisting.

[0023] Beneficial effects of the present invention: The present invention obtains a steel cord with a stable 1+4 structure by adjusting the diameters of the center core steel wire and the outer sheath steel wire and the ratio of their diameters, while allowing gaps for rubber penetration to be formed between adjacent sheath steel wires. By adjusting the diameters of the outer sheath steel wires, the rubber can fully penetrate into the gaps, reducing the air content in the steel cord. On the one hand, this avoids point contact friction between the layers of steel wires due to insufficient rubber penetration, thereby avoiding the problem of failure of the steel cord's bearing capacity due to wear; on the other hand, it avoids moisture that penetrates into the steel cord from external injuries on the tire surface from penetrating into the gaps inside the hollow steel cord, thereby effectively improving the tire's corrosion resistance, fatigue resistance and impact resistance, and increasing the tire's service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic structural diagram of a steel cord with a 1+4 structure according to the present invention;

[0025] FIG2 is a schematic diagram of the structure of a steel cord having an existing product structure (coreless steel wire), referred to as a 4×1 structure;

[0026] FIG3 is a schematic diagram of the process for producing a steel cord according to the present invention;

[0027] FIG4 is a schematic diagram of a structure in which 1+4 steel cords slide in the prior art;

[0028] FIG5 is a schematic diagram showing the effect of the size of the gap L on the penetration of rubber fluid, wherein FIG5(a) is a steel cord having a 4×1 structure in the prior art, FIG5(b) is a schematic diagram showing the effect of rubber fluid penetration of a steel cord having a 1+4 structure according to the present invention, and FIG5(c) is an enlarged schematic diagram of position E in FIG5(b);

[0029] Among them: 10-core steel wire, 20-sheath steel wire, 30-steel cord. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The application principle of the present invention is described in detail below with reference to the accompanying drawings.

[0032] The structure of the steel cord made by the present invention is shown in Figure 1. The steel cord 30 includes a core steel wire 10 located in the center, and M sheath steel wires 20 arranged around the central core steel wire 10 and tangent to the outer peripheral surface of the core steel wire 10, and there are at least two gaps L between the M sheath steel wires; the diameter d of the core steel wire 10 is smaller than the diameter d1 of the sheath steel wire 20.

[0033] Specifically, since the steel cord 30 used in the radial tire meets the tire cord strength requirements, further improving the glue penetration performance will help extend the tire service life.

[0034] The width of the gap L is adjusted by adjusting the ratio of d to d1. In the present invention, the ratio of d to d1 is between 0.420 and 0.640 to avoid the sliding of the outer sheath steel wire 20 causing the gap L to aggregate, causing the total size of the aggregated gap L to be larger than the size of the core steel wire 10, which may cause the center core steel wire 10 to slide to the outer layer and form a tight structure.

[0035] On this basis, in order to allow the rubber to fully penetrate into the gap L, the size of the gap L is controlled by adjusting the sheath steel wire diameter d1, wherein the sheath steel wire diameter d1 is between 0.20mm and 0.44mm, and the average width of the gap L is obtained to be not less than 0.0008mm.

[0036] More preferably, the ratio of d to d1 is between 0.462 and 0.640, so that the average width of the gap L is not less than 0.006 mm.

[0037] Specifically, adjustments can be made according to the following two situations:

[0038] When the sheath wire diameter d1 is between 0.20 mm and 0.30 mm, the size of the gap L needs to be increased to improve the success rate of glue penetration, so the above 0.521 < (d / d1) < 0.640. The above L is controlled to be at least 0.015 mm.

[0039] When the sheath wire diameter d1 is between 0.30 mm and 0.44 mm, the size of the gap L can be appropriately reduced to ensure complete penetration of the rubber. Therefore, 0.462<(d / d1)<0.640, and the size of the gap L can be controlled at 0.010 mm or above.

[0040] The steel cord 30 of this structure has the following advantages,

[0041] (1) A double-layer 1+M structure is adopted, and the diameter of the middle core wire 10 is smaller than that of the sheath wire 20, so as to avoid the center single wire being the main part bearing mechanical impact and reduce the possibility of the steel cord 30 breaking.

[0042] (2) By adjusting the ratio of d and d1, on the one hand, a quadrilateral with a stable cross-section structure can be obtained, as shown in Figure 4a, avoiding the displacement of the sheath steel wire 20, so that the central core steel wire 10 is exposed to the outer layer, forming a pentagon with poor rubber permeability and irregular structure, as shown in Figure 4b; on the other hand, the two connected sheath steel wires 20 do not contact each other, and the gap L left between the two facilitates the infiltration of rubber.

[0043] (3) Through the above regulation, the width of the gap L can be adjusted while ensuring the structural stability of the steel cord 30 itself. Since the width of the gap L is the narrowest position for the rubber body wrapped in the steel cord 30, it is not only the location of the rubber infiltration port, but also a position similar to the bottleneck port, such as the E position in Figure 5b. Due to the high viscosity and poor fluidity of the rubber fluid, during the infiltration process, the rubber fluid is easily blocked at the bottleneck port, forming an internal cavity between the bottleneck port and the middle core steel wire 10, such as the F position in Figure 5c, making the structure of the tire cord layer uneven, and also avoiding the occurrence of steel wire corrosion caused by water infiltration in the later stage. Secondly, the diameter of the core steel wire 10 and the sheath steel wire 20 will also affect the infiltration of the rubber fluid, especially the diameter of the sheath steel wire 20. When the rubber fluid penetrates the steel cord 30, the ideal flow is that the rubber fluid first flows inward along the surface of the sheath steel wire 20 to the surface of the core steel wire 10, and then fills the core steel wire 10 from the bottom. Since the surface curvatures of the core steel wire 10 and the sheath steel wire 20 are different, the ductility of the fluid on their respective surfaces is also different. The diameter of the sheath steel wire 20 used in the present invention is larger than the diameter of the core steel wire 10, which can enable the rubber fluid to flow to the position where the core steel wire 10 and the sheath steel wire 20 contact the vertex angle, and the gap at the vertex angle is completely filled. At the same time, the ratio of d and d1 is adjusted according to the diameter of the sheath steel wire 20, thereby adjusting the size of the gap L at the bottleneck position. Under the premise of meeting the effective penetration of the rubber fluid, a more stable steel cord structure is obtained.

[0044] The steel cord 30 corresponding to the 1+4 structure is manufactured according to the following process.

[0045] Process flow:

[0046] Raw materials → rough drawing → heat treatment of medium wire → medium drawing → heat treatment and electroplating → wet drawing → braiding and twisting → finished product;

[0047] Raw materials:

[0048] It is a steel wire rod having the following composition: a minimum carbon content of 0.60% (for example, at least 0.72% or at least 0.80% or at least 0.86% or at least 0.92%); a manganese content ranging from 0.20% to 0.90%; a silicon content ranging from 0.15% to 0.90%; a maximum sulfur content of 0.03%; a maximum phosphorus content of 0.30%; in order to reduce the amount of deformation required to obtain a predetermined tensile strength, elements such as chromium (up to 0.1 to 0.4%) and boron may also be added; the remainder is iron, and all percentages are weight percentages.

[0049] Steel wire rod is drawn through rough drawing, intermediate drawing, and wet drawing steps to the desired final diameter. The final diameter of the steel wire ranges from 0.10 mm to 0.44 mm. One or two heat treatment steps, such as sorbitization, may be performed between these drawing steps.

[0050] The steel wire is electroplated before wet drawing so that the steel wire has a coating that improves rubber adhesion. The coating is, for example, a composite of copper and zinc with different percentages, where the percentages are by weight.

[0051] The braiding and twisting can be manufactured by a tubular stranding machine or a double-twist stranding machine, preferably a double-twist machine, as shown in Figure 3. One core steel wire 10 and M sheath steel wires 20 are paid out at the same time, the pay-out tension of each steel wire in the M sheath steel wires 20 is equal, and the pay-out tension of the core steel wire 10 is greater than the average pay-out tension of the M sheath steel wires 20. When all the steel wires pass through the branching device a, the core steel wire 10 is located at the center of the branching disk, and the M sheath steel wires 20 are evenly distributed 360° around the core steel wire 10. They pass through the bundling position b and the steel cord structure stabilization device c together and then are twisted in the S direction and with a twist length of 20 mm (the sheath steel wire d1 is 0.415 mm) or a twist length of 16 mm (the sheath steel wire d1 is 0.280 mm). The steel wire bundle finally becomes a steel cord 30 after passing through the stress relief device d.

[0052] Results

[0053] Take the 1+4 structure as an example

[0054] Examples 1-5, 7-11: According to the parameter relationships corresponding to the various examples shown in Table 1, the steel cord 30 was manufactured by adjusting the structure of the steel cord 30.

[0055] Table 1

[0056]

[0057] The lower the pressure drop in the rubber penetration test in Table 1, the better the rubber penetration performance; a pressure drop of 0% indicates complete rubber penetration. For a specific method of rubber penetration pressure drop, please refer to Chinese patent application publication CN102666972A.

[0058] The larger the rubber coverage in the rubber penetration test in Table 1, the better the rubber penetration performance; 100% coverage is complete rubber penetration. The specific rubber penetration test coverage method is: cut a section of steel cord and place it in a mold box where rubber has been placed, then cover the other side of the placed steel cord with rubber. After a certain period of high temperature and high pressure, a steel cord sample solidified in the rubber is formed. Cut a 25mm sample, peel off the sheath steel wire, measure the approximate length J and width K of the uncoated part of the sheath steel wire M, calculate the area of ​​the uncoated steel wire, divide it by the total area of ​​all steel wires obtained by multiplying the approximate width of the uncoated part by 25mm, and get the percentage of the uncoated part. Subtract this percentage from 1 to get the coverage percentage. See Formula 1 for details:

[0059] [1-(J1*K1+J2*K2+…+J M *K M ) / (K1+K2+…+K M )*25]×100%

[0060] Table 1 clearly demonstrates that the rubber penetration performance of steel cords has been significantly improved compared to existing products. With existing products, rubber is virtually impermeable, making it very easy for the steel cord to rust. The open structure of the steel cord of the present invention allows for excellent rubber penetration, effectively preventing steel rust and extending the tire's service life. The ratio of the core wire diameter to the sheath wire diameter determines the width of the gap L and, therefore, the difference in rubber penetration performance.

[0061] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

DEPCT651. A steel wire assembly consisting of: a steel wire of a defined central position with diameter d; a sheath steel wire M arranged around the central steel wire, in contact with the steel wire, with diameter d1, at least two gaps L between the sheath steel wires M, where M is 4; d, d1, and L correspond to the following relationship: 0.420 < (d / d1) < 0.800; d1 is between 0.20 mm and 0.44 mm; and L is greater than or equal to 0.0008 mm.

2. The steel wire 1. Steel wire according to claim 1, where d, d1, and L satisfy the following relationships: 0.462 < (d / d1) < 0.640; and L is greater than or equal to 0.006 mm.

3. Steel wire according to claim 2, where d1 is between 0.20 mm and 0.30 mm; and 0.521 < (d / d1) < 0.

640.

4. Steel wire according to claim 3, where L is greater than or equal to 0.015 mm.

5. Steel wire according to claim 2, where d1 is between 0.30 mm and 0.44 mm; and 0.462 < (d / d1) < 0.

640.

6. Steel wire according to claim 5, where L is greater than or equal to 0.010 mm. 7.Steel wires according to one of the claims 1 through 6, where the twisting length of the steel wire in the M sheath layer is 5-25 mm, and the twisting direction is either S or Z8. Manufacturing method for steel wires according to claim 7, where in the twisting process, the steel wire and the steel wire in the M sheath layer are untwisted simultaneously, the untwisting tension of the steel wire in the sheath layer is equal, and the untwisting tension of the steel wire is greater than the tension of each individual steel wire in the sheath layer; and the steel wire is placed in the center, and the steel wire in the M sheath layer is evenly distributed at 360 degrees and bundled together around the steel wire for twisting-----------------------------------------------------------;.