Application of a microalloyed 82C wire rod in UT structural steel cord

Abstract

The present invention discloses an application of a microalloyed 82C wire rod in a UT structural steel cord, comprising: (1) drawing a Φ5.5 mm wire rod to obtain a Φ2.25 mm intermediate drawn steel wire; (2) processing the Φ2.25 mm intermediate drawn steel wire to obtain a brass-plated steel wire; (3) drawing the Φ2.25 mm brass-plated steel wire into a Φ0.35 wet drawn steel wire through a wet drawing device, wherein the wet drawing device comprises a single-mode for the 1st to 18th passes, a double-mode for the 19th to 24th passes, and an auxiliary mode. , exit die, in the double die of the 19th-24th pass, the die diameter of the auxiliary die is half of the sum of the die diameter of the previous pass + the die diameter of the current pass, and the auxiliary die is located between the previous pass and the current pass, the die diameter of the auxiliary die is half of the sum of the die diameter of the 24th pass and the exit die, the number of winding coils of the 1st-11th pass is 3.5, the number of winding coils of the 12th pass is 3.0, the number of winding coils of the 13th-23rd pass is 2.5, and the number of winding coils of the 24th pass is 2.0. Reduce the broken wire rate, improve the yield rate, and realize the wide application of 82D2Cr wire rod to replace 92C wire rod in UT structural steel cord, significantly reducing production costs.

Description

Technical Field

[0001] The invention relates to the application of 82C wire rod in UT structural steel cord, and in particular to the application of micro-alloyed 82C wire rod in UT structural steel cord. Background Art

[0002] The development of steel cord strength for tires from low to high is the natural demand and development direction of the tire industry and steel cord industry from the perspective of improving product quality and performance. Summarizing the development path of steel cord strength, the steel cords that have been industrialized in the tire industry include NT, HT, ST, and UT. At present, in the production of domestic semi-steel radial tires, NT steel cords have basically withdrawn from the market, and HT and ST steel cords are widely used, with UT steel cords used in small quantities. As steel cords for important skeleton materials of tires, UT structural steel cords are new materials that have attracted attention in recent years. The unique advantages of UT structural steel cords, such as high strength and low linear density, are just in line with the current development trend of green tires. By applying UT structural steel cords, tire companies can reduce the amount of steel cords and rubber materials used to achieve the purpose of lightweight tires, reduce rolling resistance, improve fuel efficiency, increase cruising range, and reduce carbon emissions. UT structural steel cord usually uses high carbon steel 92C wire rod as raw material. The production process of high carbon steel wire rod is constantly optimized towards environmental protection, and the price is constantly increasing. Therefore, the production cost of UT structural steel cord is also getting higher and higher, and the profit is falling sharply.

[0003] In order to solve the above problems, the present invention proposes an application of micro-alloyed 82C wire rod in UT structural steel cord. The tensile strength of the steel cord is mainly affected by the material of the steel wire rod, and the heat treatment and drawing process will also have a certain impact. The chromium content is increased, and the wire rod can improve the material structure and performance after chromium alloying. Adding chromium alloying can effectively inhibit the precipitation of eutectoid phase, improve the conversion rate of troostite, and achieve high strength and high toughness of the material; under the premise of ensuring the quality of UT structural steel cord, Cr micro-alloyed 82C wire rod, that is, 82D2Cr replaces 92C to develop UT cord specifications, which can effectively reduce production costs. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention proposes an application of micro-alloyed 82C wire rod in UT structural steel cord, which reduces the wire breakage rate and improves the yield rate, and realizes the wide application of 82D2Cr wire rod replacing 92C wire rod in UT structural steel cord, which significantly reduces the production cost.

[0005] The technical solution adopted by the present invention is: an application of a microalloyed 82C wire rod in a UT structural steel cord, (1) drawing a Φ5.5mm wire rod to obtain a Φ2.25mm intermediate drawn steel wire;

[0006] (2) Processing the above-mentioned Φ2.25 mm medium-drawn steel wire to obtain a brass-plated steel wire;

[0007] (3) A Φ2.25 mm brass-plated steel wire is drawn into a Φ0.35 mm wet-drawn steel wire by a wet-drawing device. The wet-drawing device includes a single die for the 1st to 18th passes, a double die for the 19th to 24th passes, an auxiliary die, and an exit die. In the double die for the 19th to 24th passes, the die diameter of the auxiliary die is half of the sum of the die diameter of the previous pass + the die diameter of the current pass, and the auxiliary die is located between the previous pass die and the current pass die. The die diameter of the auxiliary die is half of the sum of the diameters of the 24th pass die and the exit die. The number of winding turns for the 1st to 11th passes is 3.5 turns, the number of winding turns for the 12th pass die is 3.0 turns, the number of winding turns for the 13th to 23rd pass die is 2.5 turns, and the number of winding turns for the 24th pass die is 2.0 turns.

[0008] Based on the above scheme, as a preferred embodiment, in step (1), the Φ5.5mm 82D2Cr wire rod is pulled to the servo direct-drive wire drawing machine by the wire take-up frame, and after 9 passes of die drawing, a Φ2.25mm medium-drawn steel wire is obtained, and the tensile strength is 1811±50N / mm 2 .

[0009] Based on the above scheme, as a preference, the mold diameters of the 9-pass molds are 4.95, 4.34, 3.85, 3.44, 3.09, 2.80, 2.56, 2.38, and 2.25 respectively.

[0010] Based on the above scheme, as a preferred embodiment, in step (2), the intermediate drawn steel wire is treated in the alloying process to obtain a tensile strength of 1250~1270N / mm 2 , brass-plated steel wire with copper content of 62.5~64.0% and surface reduction ≥40%.

[0011] On the basis of the above scheme, preferably, the lubricating liquid used in the wet pulling equipment has a copper ion concentration of 600-800 ppm, a zinc ion concentration of 500-700 ppm, and a fatty acid concentration of 50-60%.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention uses 82D2Cr wire rod to replace 92C to reduce production costs; the chromium content is increased, and the wire rod can significantly improve the material structure and performance after chromium alloying, achieving high strength and high toughness of the material; at the same time, the semi-finished process, wet drawing process, and lubricant concentration parameters are optimized, and the wire breakage rate in the entire production process of UT structural steel cord is reduced and the yield rate is improved while ensuring the quality and performance of the steel cord. The wide application of 82D2Cr wire rod in UT structural steel cord has been achieved, making an important contribution to the lightweight development of tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the microstructure of brass plated steel wire at different line speeds.

[0015] Figure 2 It is the fracture morphology of the steel wire.

[0016] Figure 3 It is the elongation curve after the mold chain design is optimized.

[0017] Figure 4 It is the slip curve after the mold chain design is optimized.

[0018] Figure 5 It is the physical property diagram of wet drawn steel wire under different numbers of double modes;

[0019] Figure 6 This is a comparison chart of the wire breakage rate during the wet drawing process and the original process;

[0020] Figure 7 This is a comparison chart of the broken wire rate during the plying process and the original process. DETAILED DESCRIPTION

[0021] The present invention will be further described below by way of examples, but the scope of the present invention is not limited thereto.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0023] like Figure 1-7 As shown, taking the production of 2+2x0.35UT structural steel cord as an example, the specific steps include:

[0024] (1) The Φ5.5mm 82D2Cr wire rod is pulled onto the servo direct-drive wire drawing machine by the wire take-up frame, and drawn through 9 passes of dies (4.95-4.34-3.85-3.44-3.09-2.80-2.56-2.38-2.25mm) to obtain a Φ2.25mm medium-drawn steel wire with a breaking force of 7200N and a tensile strength of 1811N / mm 2 .

[0025] (2) The above-mentioned Φ2.25 mm medium-drawn steel wire is passed through a heating furnace, an electroplating process, and an AQ water bath in the alloying process to obtain a tensile strength of 1250~1270N / mm 2, brass-plated steel wire (2.25HTCr) with a copper content of 62.5~64.0% and a surface shrinkage of ≥40%; at the same time, different line speed comparison tests were carried out on the alloy process to ensure that the brass-plated steel wire has uniform microstructure and good surface quality, providing high-quality raw materials for the wet drawing process. The line speed test was carried out at 33m / min, 34m / min, 35m / min, and 36m / min (ie DV: 74.2, 76.5, 78.8, and 81) for parallel comparison. Through this line speed test, it can be seen that the brass-plated steel wire 2.25HTCr produced at 34m / min has good microstructure and low wire breakage frequency during wet drawing. The SEM photos of the microstructure (four directions, core) are as follows Figure 1 shown.

[0026] The Φ2.25mm brass-plated steel wire is drawn into a Φ0.35 wet-drawn steel wire through wet-drawing equipment; the friction coefficient of the steel wire between the dies of each pass is reduced by optimizing the die chain design; the wire is wound in a 3.5-3.0-2.5-2.0 manner to reasonably distribute the tension between each pass and reduce the risk of wire breakage during the drawing process. At the same time, a comparative test of different groups of double modes is carried out on the wet-drawing process to reduce the frequency of wire breakage of the brass-plated steel wire during the drawing process, reduce the wire temperature, and make the produced wet-drawn steel wire have good performance and stable quality. In this test of different groups of double modes, 3 groups of double modes + 1 auxiliary, 4 groups of double modes + 1 auxiliary, 5 groups of double modes + 1 auxiliary, 6 groups of double modes, and 6 groups of double modes + 1 auxiliary (simply: 3+1, 4+1, 5+1, 6+0, 6+1) were used for verification, and the physical properties of the wet-drawn steel wire Φ0.35 were obtained. The die chain design is as follows:

[0027]

[0028] Through this dual-mode test, it can be seen that the physical properties and quality of the wet-drawn steel wire of Φ0.355 mm drawn from Φ2.25 mm brass-plated steel wire using 6 sets of dual-mode + 1 auxiliary (Dies) (abbreviated as 6+1) are the most stable.

[0029] (4) The wet-drawing lubrication conditions were further optimized, the wet-drawing equipment was modified, a copper ion separator was added, and the concentrations of copper ions, zinc ions, and fatty acids in the lubricating fluid were adjusted to improve the lubricating effect of the lubricating fluid, so as to ensure that the performance and quality of the wet-drawn steel wire of Φ2.25mm brass-plated steel wire drawn to Φ0.35 reached the optimal conditions. The wire breakage rate in the wet-drawing process was reduced from 1.0 times / ton to 0.5 times / ton, providing the cord with wet-drawn steel wire with stable quality. In this experiment, the concentration parameters of the wet-drawing lubricant were adjusted to improve the drawing effect of 6 groups of dual modes + 1 auxiliary and to reduce the wire breakage rate in the wet-drawing process. By adjusting the concentration of the lubricating fluid for parallel comparison tests, the physical properties of the Φ0.355 wet-drawn steel wire were obtained as follows:

[0030]

[0031] Through this wet-drawing lubricant test, it can be known that copper ion concentration of 600~800ppm, zinc ion concentration of 500~700ppm, and fatty acid concentration of 50~60% are the optimal lubrication conditions for drawing Φ2.25mm brass-plated steel wire to Φ0.355 wet-drawn steel wire.

[0032] Lubricant name: SUPERSOL ADM U V2 Lubricant for Wire Drawing, Model: ADV240511. When in use, adjust the concentrations of copper ions, zinc ions, and fatty acids through the lubrication circulation system. When the concentration is too high, reduce the content of copper ions and zinc ions through a copper ion separator or drain the old lubricant at the bottom of the waste liquid pool, and then add pure water to dilute it in the return liquid pool. When the fatty acid concentration is too low, add fresh lubricant (with a high fatty acid concentration initially) to the return liquid pool for replenishment.

[0033] (5) Combined with the above process optimization, the Φ2.25mm brass-plated steel wire is drawn into a wet-drawn steel wire with a diameter of Φ0.35 to produce 2+2x0.35UT steel cord. Two Φ0.35 monofilaments are used as the core wire and two Φ0.35 monofilaments are used as the outer layer. The required finished 2+2x0.35UT structural steel cord is obtained by double twisting. The wire breakage rate during the plying process of 82D2Cr wire rod in producing 2+2x0.35UT structural steel cord is reduced from 7.5 times / ton to 6.0 times / ton, and the wire breakage problem is significantly improved. The performance meets customer requirements and is basically consistent with 92C. Both meet customer needs. The test performance of 2+2x0.35UT specification is as follows:

[0034]

[0035] In combination with the above 2+2x0.35UT embodiment, it can be seen that the UT structural steel cord obtained by the method of the present invention not only reduces the production cost, but also reduces the wire breakage rate in the entire production process and improves the yield rate while ensuring that the performance meets the customer standards.

[0036] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. Application of microalloyed 82C wire rod in UT structural steel cord, characterized in that: (1) Drawing Φ5.5mm 82D2Cr wire rod to obtain Φ2.25mm medium-drawn steel wire; (2) Processing the above-mentioned Φ2.25 mm medium-drawn steel wire to obtain a brass-plated steel wire; (3) A Φ2.25 mm brass-plated steel wire is drawn into a Φ0.35 mm wet-drawn steel wire by a wet-drawn device. The wet-drawn device includes a single die for the 1st to 18th passes, a double die for the 19th to 24th passes, an auxiliary die, and an exit die. In the double die for the 19th to 24th passes, the die diameter of the auxiliary die is half of the sum of the die diameter of the previous pass + the die diameter of the current pass, and the auxiliary die is located between the previous pass die and the current pass die. The die diameter of the auxiliary die is half of the sum of the diameters of the 24th pass die and the exit die. The number of winding turns for the 1st to 11th passes is 3.5 turns, the number of winding turns for the 12th pass die is 3.0 turns, the number of winding turns for the 13th to 23rd pass die is 2.5 turns, and the number of winding turns for the 24th pass die is 2.0 turns.

2. The application of a microalloyed 82C wire rod in UT structural steel cord according to claim 1, characterized in that: In step (1), the Φ5.5mm 82D2Cr wire rod is pulled onto the servo direct drive wire drawing machine by the wire take-up frame, and after 9 passes of die drawing, a Φ2.25mm medium drawn steel wire is obtained, and the tensile strength is 1811±50N / mm 2 .

3. The application of a microalloyed 82C wire rod in UT structural steel cord according to claim 2, characterized in that: The mold diameters of the 9-pass molds are 4.95mm, 4.34mm, 3.85mm, 3.44mm, 3.09mm, 2.80mm, 2.56mm, 2.38mm, and 2.25mm respectively.

4. The application of a microalloyed 82C wire rod in UT structural steel cord according to claim 1, characterized in that: In step (2), the intermediate drawn steel wire is processed in the alloying process to obtain a tensile strength of 1250~1270N / mm 2 , brass-plated steel wire with copper content of 62.5~64.0% and surface reduction ≥40%.

5. The application of a microalloyed 82C wire rod in UT structural steel cord according to claim 4, characterized in that: The line speed in the alloying process is 34 m / min.

6. The application of a microalloyed 82C wire rod in UT structural steel cord according to claim 1, characterized in that: The lubricating fluid used in the wet pulling equipment has a copper ion concentration of 600~800ppm, a zinc ion concentration of 500~700ppm, and a fatty acid concentration of 50~60%.

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