A method for producing an outer filament of a steel cord

Abstract

The application discloses a production method of steel cord outer winding wire, adopts 62C wire rod as raw material, the composition of the wire rod comprises the following components in percentage by mass: C: 0.60-0.65; Si: 0.15-0.30; Mn: 0.45-0.60; P: <=0.025; S: <=0.020; P+S: <=0.040; Cr: <=0.15; Ni: <=0.15; Cu: <=0.15; Al t : <=0.010, the balance is Fe and inevitable impurities; by reducing the carbon content in the wire rod, the plasticity and drawing processing performance of the wire rod are improved, so that the intermediate heat treatment process is omitted, and the 5.5mm wire rod is directly continuously drawn to about 1.0mm through rough drawing and intermediate drawing. Compared with the prior art, the larger processing deformation ensures that the wire rod has sufficient strength after drawing, so that the mechanical properties of the steel wire are ensured, the process flow is simplified, energy consumption is saved, and production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of steel cord technology, and more particularly to a method for producing steel cord with external winding. Background Technology

[0002] Externally wound steel cord is a widely used steel cord specification. The traditional production process involves drawing 5.5mm diameter 72C wire rod to 2.9–3.25mm through rough drawing, followed by an intermediate heat treatment and further drawing to approximately 0.76mm. This is then followed by heat treatment and brass plating, wet drawing to 0.15mm, and finally winding the cord into a rope. The limitation of this process is that after drawing the 72C wire rod to 2.9–3.25mm, the internal structure deforms and can no longer support further drawing. An intermediate heat treatment is necessary before proceeding to the next step, increasing energy, labor, and material consumption, thus raising the production cost of externally wound steel cord. Summary of the Invention

[0003] The purpose of this invention is to provide a method for producing externally wound steel cord. This method uses 62C wire rod instead of 72C wire rod and eliminates the intermediate heat treatment process. By reducing the carbon content in the wire rod, its plasticity and drawing performance are improved, thus eliminating the need for intermediate heat treatment. The 5.5mm wire rod is directly drawn to approximately 1.0mm through coarse and intermediate drawing. Compared to existing processes, the greater deformation ensures sufficient strength of the wire rod after drawing. This simplifies the process, saves energy, and reduces production costs while maintaining the mechanical properties of the steel wire.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for producing outer winding wire for steel cord, using 62C wire rod as raw material. The composition of the wire rod, by mass percentage, includes: C: 0.60-0.65; Si: 0.15-0.30; Mn: 0.45-0.60; P: ≤0.025; S: ≤0.020; P+S: ≤0.040; Cr: ≤0.15; Ni: ≤0.15; Cu: ≤0.15; Al t ≤0.010, balance is Fe and unavoidable impurities.

[0006] Specifically, the steps include the following:

[0007] Coarse drawing: The wire rod is coarsely drawn to 3.25mm;

[0008] 2) Intermediate drawing: The wire rod after rough drawing is not heat-treated and is intermediately drawn to 1.0mm;

[0009] 3) Heat treatment and electroplating: The obtained medium-drawn steel wire is heat-treated in a heat treatment furnace and quenched in AQ liquid to form a sorbite and a small amount of coarse lamellar pearlite microstructure; then, it is subjected to copper plating, zinc plating, and MF diffusion to obtain a brass alloy coating, in which the copper content accounts for approximately 63.5%;

[0010] 4) Wet drawing: The above-mentioned brass-plated steel wire is drawn to a single wire with a diameter of 0.15mm through a wet drawing process;

[0011] 5) Wire forming: The 0.15mm monofilament obtained by wet drawing is used as the outer winding wire to produce steel cord;

[0012] 6) Warehousing: After the production of the cord is completed, performance testing is conducted. After passing the inspection, the cords are packaged and stored according to different specifications. Beneficial effects of this invention:

[0013] The method for producing steel cord outer winding of the present invention uses 62C wire rod instead of 72C wire rod and eliminates the intermediate heat treatment step in the production of outer winding wire. The sample testing of each process in the production process meets the standard requirements.

[0014] The present invention provides a method for producing steel cord outer winding. This invention simplifies the production process, reduces energy consumption, improves production efficiency, is more in line with the concept of green and environmentally friendly production, and effectively reduces production costs. Attached Figure Description

[0015] Figure 1 This is a comparison chart showing the wire breakage rate of steel cord obtained according to Embodiments 1, 2, and 3 of the present invention during the drawing process with that of the original process. Detailed Implementation

[0016] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0017] Example 1: A production process for producing externally wound wire by replacing 72C wire rod with 62C wire rod and eliminating the intermediate heat treatment step, specifically including the following steps:

[0018] Using 62C wire rod as raw material, the composition of the wire rod, by weight percentage, includes: C: 0.61%; Si: 0.17%; Mn: 0.42%; P: 0.015%; S: 0.009%; Cr: 0.08%; Ni: 0.01%; Cu: 0.01%; Al t : 0.001%, balance being Fe and unavoidable impurities.

[0019] 1) Coarse drawing: First, the oxide scale on the surface of the wire rod is removed by mechanical means combined with pickling. Then, after boron coating and drawing, a steel wire with a diameter of 3.25mm is obtained and wound on the take-up frame.

[0020] 2) Intermediate drawing: The coarse-drawn steel wire is drawn through 10 passes of dies to obtain an intermediate-drawn steel wire with a diameter of 1.0 mm.

[0021] 3) Heat treatment and electroplating: The medium-drawn steel wire is sequentially degreased, heat treated, quenched in AQ solution, pickled, copper plated, zinc plated, hot water washed, MF medium-frequency diffusion, phosphoric acid washed, and soaped to obtain copper-plated steel wire with a diameter of 1.0 mm. The surface of the steel wire is plated with a brass coating with a copper content of about 63.5%.

[0022] 4) Wet drawing: The copper-plated steel wire is drawn to 0.15mm through 23 passes of dies, with a breaking tensile force of about 50N.

[0023] 5) Threading: Wet-drawn monofilaments are used as outer windings for 3+9+15x0.225+0.15HT.

[0024] 6) Warehousing: After the finished cord products pass inspection, they are packaged and stored.

[0025] The wire breakage rate of the 3+9+15x0.225+0.15HT steel cord obtained in this embodiment is about 2.8 times / ton, while the original process had a wire breakage rate of about 3.0 times / ton, showing comparable performance. The average breaking strength of the finished cord is 3285N (standard ≥3120N).

[0026] Example 2: A production process for producing externally wound wire using 62C wire rod instead of 72C wire rod while eliminating the intermediate heat treatment step, specifically including the following steps:

[0027] Using 62C wire rod as raw material, the composition of the wire rod, by mass percentage, includes: C: 0.61%; Si: 0.17%; Mn: 0.42%; P: 0.015%; S: 0.009%; Cr: 0.08%; Ni: 0.01%; Cu: 0.01%; Al t : 0.001%, balance being Fe and unavoidable impurities.

[0028] 1) Coarse drawing: First, the oxide scale on the surface of the wire rod is removed by mechanical means combined with pickling. Then, after boron coating and drawing, a steel wire with a diameter of 3.25mm is obtained and wound on the take-up frame.

[0029] 2) Intermediate drawing: The coarse-drawn steel wire is drawn through 10 passes of dies to obtain an intermediate-drawn steel wire with a diameter of 1.0 mm.

[0030] 3) Heat treatment and electroplating: The medium-drawn steel wire is sequentially degreased, heat treated, quenched in AQ solution, pickled, copper plated, zinc plated, hot water washed, MF medium-frequency diffusion, phosphoric acid washed, and soaped to obtain copper-plated steel wire with a diameter of 1.0 mm. The surface of the steel wire is plated with a brass coating with a copper content of about 63.5%.

[0031] 4) Wet drawing: The copper-plated steel wire is drawn to 0.15mm through 23 passes of dies.

[0032] 5) Threading: Wet-drawn monofilaments are used as outer windings for 3+9+15x0.175+0.15NT.

[0033] 6) Warehousing: After the finished cord products pass inspection, they are packaged and stored.

[0034] The wire breakage rate of the 3+9+15x0.175+0.15NT steel cord obtained in this embodiment is about 1.1 times / ton, while the original process had a wire breakage rate of about 1.2 times / ton. The wire breakage rates are comparable, and the average breaking strength of the finished cord is 1905N (standard ≥1750N).

[0035] Example 3: A production process for producing externally wound wire using 62C wire rod instead of 72C wire rod while eliminating the intermediate heat treatment step, specifically including the following steps:

[0036] Using 62C wire rod as raw material, the composition of the wire rod, by mass percentage, includes: C: 0.61%; Si: 0.17%; Mn: 0.42%; P: 0.015%; S: 0.009%; Cr: 0.08%; Ni: 0.01%; Cu: 0.01%; Al t : 0.001%, balance being Fe and unavoidable impurities.

[0037] 1) Coarse drawing: First, the oxide scale on the surface of the wire rod is removed by mechanical means combined with pickling. Then, after boron coating and drawing, a steel wire with a diameter of 3.25mm is obtained and wound on the take-up frame.

[0038] 2) Intermediate drawing: The coarse-drawn steel wire is drawn through 10 passes of dies to obtain an intermediate-drawn steel wire with a diameter of 1.0 mm.

[0039] 3) Heat treatment and electroplating: The medium-drawn steel wire is sequentially degreased, heat treated, quenched in AQ liquid, pickled, copper plated, zinc plated, hot water washed, MF medium-frequency diffusion, phosphoric acid washed, and soaped to obtain copper-plated steel wire with a diameter of 1.0 mm. The surface of the steel wire is plated with a brass coating with a copper content of about 63.5%.

[0040] 4) Wet drawing: The copper-plated steel wire is drawn to 0.15mm through 23 passes of dies.

[0041] 5) Threading: Wet-drawn monofilaments are used as outer windings for 3+9x0.22+0.15HT.

[0042] 6) Warehousing: After the finished cord products pass inspection, they are packaged and stored.

[0043] The wire breakage rate of the 3+9x0.22+0.15HT steel cord obtained in this embodiment is about 3.3 times / ton, while the original process has a wire breakage rate of about 3.2 times / ton, and the wire breakage performance is comparable; the average breaking force of the finished cord is 1481N (standard ≥1410N).

[0044] The above embodiments combined Figure 1 As can be seen, this invention proposes a production process for externally wound wire using 62C wire rod instead of 72C wire rod while eliminating the intermediate heat treatment step. The reduced carbon content of the wire rod improves its drawing performance, allowing it to be drawn directly to 1.0mm without intermediate heat treatment. Simultaneously, the increased strength resulting from greater cold working deformation compensates for the strength loss caused by the reduced carbon content, ensuring the steel wire possesses sufficient mechanical properties. In summary, this invention ensures that the steel wire meets standard requirements for strength and breaking force while reducing the carbon content of the wire rod, while also simplifying the process, eliminating the intermediate heat treatment step, reducing energy consumption, improving production efficiency, and effectively reducing production costs.

[0045] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A production method of steel cord outer wrapping wire, characterized in that: A 62C wire rod is used as a raw material, and the composition of the wire rod includes, in mass percent: C: 0.60-0.65; Si: 0.15-0.30; Mn: 0.45-0.60; P: ≤0.025; S: ≤0.020; P+S: ≤0.040; Cr: ≤0.15; Ni: ≤0.15; Cu: ≤0.15; Al t : ≤0.010, with the balance being Fe and unavoidable impurities. Specifically comprising the following steps: 1) rough drawing: the rod is drawn to 3.25mm; 2) medium drawing: the rough drawn rod is not heat treated and is drawn to 1.0mm; 3) heat treatment and electroplating: the obtained medium drawn steel wire is quenched by a heat treatment furnace and AQ liquid to form a structure of sorbite and a small amount of coarse lamellar pearlite; then it is plated with copper, zinc and MF diffusion to obtain a brass alloy plating layer, and the copper content in the plating layer accounts for 63.5%; 4) wet drawing: the steel wire with brass alloy plating layer obtained in step 3) is drawn to a single wire with a diameter of 0.15mm through a wet drawing process; 5) wire forming: the 0.15mm single wire obtained by wet drawing is used as an outer wrapping wire to produce a steel cord; 6) storage: after the production of the cord is completed, performance test is carried out, and after the test is qualified, it is packaged and stored according to different specifications.

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