A surface treatment process for steel cord before drawing

Abstract

The present application belongs to the technical field of steel cord preparation and processing, and particularly relates to a surface treatment process before drawing of steel cord wire rod. Lubricating powder is fully dispersed in boronizing liquid to form a suspension liquid as a surface treatment liquid at a concentration of 200-500 g / L. The surface of the wire rod after pretreatment is coated with the surface treatment liquid. Polyethylene wax with a melting point of 110 DEG C or above is melted and sprayed on the surface of the wire rod after the above coating treatment in a normal temperature environment to form a polyethylene wax film with a thickness of 50-300 microns, and then heated and dried at 100 DEG C-110 DEG C.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel cord preparation and processing, and particularly relates to a surface treatment process for steel cord wire rod before drawing. BACKGROUND

[0002] In the steel cord production process, the steel cord wire rod needs to be stretched and thinned to the required radial size through drawing operation. Before drawing, the wire rod surface is often first treated by boron coating, and the borax coated on the surface has certain lubricity, and the roughness of the wire rod surface after boron coating treatment is also increased, which can further increase the lubrication effect of the wire rod when the wire rod contacts with the lubricating powder before entering the drawing unit.

[0003] However, the bonding force between the metal wire rod and the borax or the lubricating powder is generally limited, so that the amount of lubricating substances that can be stably attached to the wire rod surface and enter the drawing unit with the wire rod is also limited, which often leads to insufficient lubrication of the wire rod surface during the subsequent drawing process, so that the surface quality of the steel cord formed after drawing is not ideal, such as the steel cord surface being too smooth and the combination with rubber being weak. SUMMARY

[0004] To solve the above technical problems, the present application provides a surface treatment process for steel cord wire rod before drawing,

[0005] (1) Preparation of surface treatment liquid

[0006] The lubricating powder is fully dispersed in the boronizing liquid at a concentration of 200-500 g / L to form a suspension liquid as the surface treatment liquid;

[0007] (2) Surface coating

[0008] The surface treatment liquid obtained in step (1) is coated on the surface of the pretreated wire rod;

[0009] (3) Wax spraying and fixing

[0010] After the polyethylene wax with a melting point of 110°C or higher is melted, it is sprayed on the surface of the wire rod treated in step (2) to form a polyethylene wax film with a thickness of 50-300 μm, and then heated and dried at 100-110°C.

[0011] As a preferred embodiment, the boronizing liquid in step (1) is a water solution with a mass concentration of 15-20% of Na2B4O7.

[0012] As a preferred embodiment, the lubricating powder in step (1) is sodium stearate.

[0013] As a preferred option: in step (2), the pretreatment includes mechanical peeling, acid washing, and water washing in sequence.

[0014] Preferably, in step (2), the wire rod is transferred through the surface treatment liquid obtained in step (1), and the transfer time of the wire rod in the surface treatment liquid is 5 to 10 seconds.

[0015] Furthermore: In step (2), the transmission speed of the wire rod is 0.2 to 1 m / s.

[0016] As a preferred option: In step (3), after the polyethylene wax is melted, it is sprayed onto the surface of the wire rod through a nozzle. There are three nozzles in total. The wire rod is conveyed forward in a straight line along its own length direction. The three nozzles are evenly arranged around the wire rod with the wire rod length direction as the central axis. That is, the plane enclosed by the three nozzles is perpendicular to the length direction of the wire rod. The spraying direction of each nozzle is perpendicular to the length direction of the wire rod and aligned with the wire rod.

[0017] Furthermore: The melting point of polyethylene wax is 110℃~120℃. The polyethylene wax is fully melted at 180℃~200℃ before being sprayed.

[0018] The beneficial effects of this invention are as follows:

[0019] First, in this solution, the lubricating powder is directly mixed into the borosilicate solution at a higher concentration to form a viscous oily suspension. Compared with the ability of conventional dilute borosilicate solution to carry dry lubricating powder after being coated on the surface of the wire rod, this viscous suspension, due to its significantly increased viscosity, allows the wire rod surface that passes through it to carry more and thicker lubricant material.

[0020] Considering that excessive moisture on the wire rod surface can easily lead to large-scale corrosion after drawing, it is necessary to dry the wire rod before it enters the drawing process. Existing technology also involves drying the borosilicate-coated wire rod before conveying it through the lubricant powder box and then proceeding with the drawing process. However, for this solution, due to adhesion issues on the wire rod surface, and the large amount of lubricant powder already present, direct drying would result in a significant portion of the lubricant powder falling off the wire rod after drying, thus contradicting the original intention of this solution: "more lubricant coating is more beneficial for wire rod lubrication during drawing."

[0021] In this solution, while the lubricating powder adhering to the surface of the wire rod is still wet and has not fallen off, polyethylene wax is sprayed onto its surface to form a film. Although the polyethylene wax is sprayed out in a molten state, the wire rod and the wet lubricating material on its surface are at room temperature at this time. Furthermore, by controlling the spraying parameters, the thickness of the polyethylene wax layer deposited on the wire rod is very small. Therefore, after the polyethylene wax is deposited on the wire rod, it is quickly cured upon cooling to form a coating film. At the same time, because the polyethylene wax layer deposited on the wire rod is very thin, during the cooling and curing process of this polyethylene wax deposit, based on the principle of thermal expansion and contraction of the material itself, many small pores will be formed on the deposit layer. At this point, the wire rod enters the drying and dehydration stage. During the heating and dehydration process, the vaporized water molecules are released through the small pores distributed on the deposition layer, thus drying the lubricating material and preventing the wire rod surface from rusting due to moisture during subsequent drawing. The solid lubricating powder encased in the polyethylene wax film cannot easily fall out of these small pores, so most of the lubricating material is retained. Furthermore, the drying temperature during heating and dehydration is significantly lower than the melting temperature of polyethylene wax. Therefore, during heating and dehydration, the polyethylene wax film layer does not remelt and seal these small pores, keeping the water molecule release channels unobstructed.

[0022] Even after thorough drying and dehydration, the wire rod can still carry a significant amount of lubricant during drawing. Furthermore, the polyethylene wax layer itself has a lubricating function, which can also assist in lubricating the wire rod during drawing. Attached Figure Description

[0023] Figure 1 This is a surface morphology diagram of the steel cord formed by drawing in Example 1;

[0024] Figure 2 The image shows the surface morphology of the steel cord formed by drawing in Example 1.

[0025] Figure 3 The image shows the surface morphology of the steel cord formed by the drawing process in Comparative Example 2. Detailed Implementation

[0026] A surface treatment process for steel cord wire rods before drawing.

[0027] (1) Preparation of surface treatment solution

[0028] The lubricating powder sodium stearate is fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 15% to 20% at a concentration of 200 to 500 g / L to form a suspension, which is used as a surface treatment solution.

[0029] (2) Surface coating

[0030] At room temperature (25℃, the same below), the surface treatment liquid obtained in step (1) is stirred evenly, and the wire rod that has undergone mechanical peeling, pickling and water washing pretreatment is conveyed through the surface treatment liquid at a conveying speed of 0.2 to 1 m / s. The time the wire rod passes through the surface treatment liquid is 5 to 10 s.

[0031] (3) Wax spraying for fixing

[0032] Polyethylene wax with a melting point of 110℃~120℃ is melted at 180℃~200℃ and then sprayed onto the surface of the wire rod treated in step (2) at an atomization pressure of 0.5~0.7MPa through an atomizing nozzle at room temperature to form a polyethylene wax film with a thickness of 50~300μm. There are three nozzles in total. The wire rod is conveyed forward in a straight line along its own length direction. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and aligned with the wire rod.

[0033] After the above-mentioned spraying, the wire rod is transferred to a heating and drying environment at 100℃~110℃ and left to stand for 30~90 minutes to dry completely.

[0034] Example 1

[0035] A surface treatment process for steel cord wire rods before drawing.

[0036] (1) Preparation of surface treatment solution

[0037] The lubricating powder sodium stearate (120 mesh, the same below) was fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 18% at a concentration of 280 g / L to form a suspension as a surface treatment solution.

[0038] (2) Surface coating

[0039] At room temperature, the surface treatment liquid obtained in step (1) is stirred evenly, and the SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s) and water washing (high pressure water rinsing) is transferred through the surface treatment liquid at a transfer speed of 0.4m / s. The wire rod passes through the surface treatment liquid for 7s (the surface treatment liquid is sufficient).

[0040] (3) Wax spraying for fixing

[0041] Polyethylene wax with a melting point range of 110℃~120℃ is fully melted at 200℃ and then sprayed onto the surface of the wire rod treated in step (2) through an atomizing nozzle at room temperature. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and sprays at an atomizing pressure of 0.7MPa, thereby forming an atomization zone on the transport path of the wire rod, so that a polyethylene wax film of about 150μm thick is deposited on the surface of the wire rod that has been transported.

[0042] After being sprayed, the wire rods are transferred into the drying oven and left to stand at 103°C for 80 minutes.

[0043] The wire rod after surface treatment in Example 1 is fed into a straight-line continuous wire drawing machine for cold drawing: the temperature of the wire drawing machine drum is controlled to be below 67° by cooling water, the compression angle of the wire drawing die is 8°, the sizing strip length is 5mm, the drawing speed is 1.1m / s, the single-pass compression rate is 10%, and the number of drawing passes is 13. Finally, a steel cord with a diameter of 0.25mm is drawn. The obtained steel cord is polished to remove the residual lubricating components on the surface.

[0044] Example 2

[0045] A surface treatment process for steel cord wire rods before drawing.

[0046] (1) Preparation of surface treatment solution

[0047] The lubricating powder sodium stearate was fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 15% at a concentration of 410 g / L to form a suspension, which was used as a surface treatment solution.

[0048] (2) Surface coating

[0049] At room temperature, the surface treatment liquid obtained in step (1) is stirred evenly, and the SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s) and water washing (high pressure water rinsing) is transferred through the surface treatment liquid at a transfer speed of 0.8m / s. The wire rod passes through the surface treatment liquid for 10s (the surface treatment liquid is sufficient).

[0050] (3) Wax spraying for fixing

[0051] Polyethylene wax with a melting point range of 110℃~120℃ is fully melted at 190℃ and then sprayed onto the surface of the wire rod treated in step (2) through an atomizing nozzle at room temperature. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and sprays at an atomizing pressure of 0.5MPa, thereby forming an atomization zone on the transport path of the wire rod, so that a polyethylene wax film of about 200μm thick is deposited on the surface of the wire rod that has been transported.

[0052] After being coated as described above, the wire rods are transferred into the drying oven and left to stand at 100°C for 90 minutes.

[0053] The wire rod that underwent surface treatment in Example 2 was fed into a straight-line continuous wire drawing machine for cold drawing, following the same procedure described above. Cooling water was used to control the drum temperature of the wire drawing machine to be below 67°C. The compression angle of the wire drawing die was 8°, the sizing strip length was 5mm, the drawing speed was 1.1m / s, the single-pass compression rate was 10%, and the number of drawing passes was 13. Finally, a steel cord with a diameter of 0.25mm was drawn. The resulting steel cord was polished to remove any residual lubricating components from the surface.

[0054] Example 3

[0055] A surface treatment process for steel cord wire rods before drawing.

[0056] (1) Preparation of surface treatment solution

[0057] The lubricating powder sodium stearate was fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 20% at a concentration of 500 g / L to form a suspension, which was used as a surface treatment solution.

[0058] (2) Surface coating

[0059] At room temperature, the surface treatment liquid obtained in step (1) is stirred evenly, and the SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s) and water washing (high pressure water rinsing) is transferred through the surface treatment liquid at a transfer speed of 0.2m / s. The wire rod passes through the surface treatment liquid for 5s (the surface treatment liquid is sufficient).

[0060] (3) Wax spraying for fixing

[0061] Polyethylene wax with a melting point range of 110℃~120℃ is fully melted at 190℃ and then sprayed onto the surface of the wire rod treated in step (2) through an atomizing nozzle at room temperature. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and sprays at an atomizing pressure of 0.6MPa, thereby forming an atomization zone on the transport path of the wire rod, so that a polyethylene wax film of about 240μm thick is deposited on the surface of the wire rod that has been transported.

[0062] After being coated as described above, the wire rods are transferred into the drying oven and left to stand at 100°C for 90 minutes.

[0063] The wire rod that underwent surface treatment as described in Example 3 was fed into a straight-line continuous wire drawing machine for cold drawing, following the same procedure as above. Cooling water was used to control the temperature of the wire drawing machine drum below 67°C. The compression angle of the wire drawing die was 8°, the sizing strip length was 5mm, the drawing speed was 1.1m / s, the single-pass compression rate was 10%, and the number of drawing passes was 13. Finally, a steel cord with a diameter of 0.25mm was drawn. The resulting steel cord was polished to remove any residual lubricating components from the surface.

[0064] Comparative Example 1

[0065] The process of coating the wire rod surface with a lubricating substance is replaced with the conventional process of "coating the wire rod surface with borosilicate solution and then carrying the dry lubricating powder," while the remaining operations are the same as in Example 1.

[0066] (1) Preparation of borate solution

[0067] Prepare an aqueous solution of Na2B4O7 with a mass concentration of 18% as a boriding solution;

[0068] (2) Surface coating

[0069] At room temperature, SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s), and water washing (high pressure water rinsing) are successively transported through the borosilicate solution and dried sodium stearate lubricating powder obtained in step (1) at a transmission speed of 0.4m / s. The wire rod passes through the borosilicate solution and the lubricating powder box for 7s respectively (borosilicate solution and lubricating powder are in sufficient quantity).

[0070] (3) Wax spraying for fixing

[0071] Polyethylene wax with a melting point range of 110℃~120℃ is fully melted at 200℃ and then sprayed onto the surface of the wire rod treated in step (2) through an atomizing nozzle at room temperature. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and sprays at an atomizing pressure of 0.7MPa, thereby forming an atomization zone on the transport path of the wire rod, so that a polyethylene wax film of about 150μm thick is deposited on the surface of the wire rod that has been transported.

[0072] After being sprayed, the wire rods are transferred into the drying oven and left to stand at 103°C for 80 minutes.

[0073] The wire rod that underwent surface treatment as described in Comparative Example 1 was fed into a straight-line continuous wire drawing machine for cold drawing, following the same procedure as above. Cooling water was used to control the drum temperature of the wire drawing machine to be below 67°. The compression angle of the wire drawing die was 8°, the sizing strip length was 5mm, the drawing speed was 1.1m / s, the single-pass compression rate was 10%, and the number of drawing passes was 13. Finally, a steel cord with a diameter of 0.25mm was drawn. The resulting steel cord was polished to remove any residual lubricating components from the surface.

[0074] Comparative Example 2

[0075] After drying the wire rod coated with the surface treatment liquid, it is then fixed by wax spraying. The remaining operations are the same as in Example 1.

[0076] (1) Preparation of surface treatment solution

[0077] The lubricating powder sodium stearate was fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 18% at a concentration of 280 g / L to form a suspension, which was used as a surface treatment solution.

[0078] (2) Surface coating

[0079] At room temperature, the surface treatment liquid obtained in step (1) is stirred evenly, and the SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s) and water washing (high pressure water rinsing) is transferred through the surface treatment liquid at a transfer speed of 0.4m / s. The wire rod passes through the surface treatment liquid for 7s (the surface treatment liquid is sufficient).

[0080] (3) Wax spraying for fixing

[0081] The coils coated in step (2) are transferred into the drying oven and left to stand at 103°C for 80 minutes before being transferred out of the drying oven. Polyethylene wax with a melting point range of 110°C to 120°C is fully melted at 200°C and then sprayed onto the surface of the coils that have left the drying oven through atomizing nozzles at room temperature. There are three nozzles in total. The coils are transferred forward in a straight line along their own length direction. The three nozzles are evenly arranged around the circumference of the coils with the length direction of the coils as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the coils and sprays at an atomizing pressure of 0.7MPa, thereby forming an atomization zone on the transfer path of the coils, so that a polyethylene wax film of about 150μm thick is deposited on the surface of the coils that have been transferred.

[0082] The wire rod that underwent surface treatment as described in Comparative Example 2 was fed into a straight-line continuous wire drawing machine for cold drawing, following the same procedure as above. Cooling water was used to control the drum temperature of the wire drawing machine to below 67°C. The compression angle of the wire drawing die was 8°, the sizing strip length was 5mm, the drawing speed was 1.1m / s, the single-pass compression rate was 10%, and the number of drawing passes was 13. Finally, a steel cord with a diameter of 0.25mm was drawn. The resulting steel cord was polished to remove any residual lubricating components from the surface.

[0083] Comparative Example 3

[0084] In step (3), when performing wax spraying for fixation, the thickness of the wax film deposition is increased, and the drying time after wax spraying for fixation is extended. All other operations are the same as in Example 1.

[0085] (1) Preparation of surface treatment solution

[0086] The lubricating powder sodium stearate was fully dispersed in an aqueous solution of Na2B4O7 with a mass concentration of 18% at a concentration of 280 g / L to form a suspension, which was used as a surface treatment solution.

[0087] (2) Surface coating

[0088] At room temperature, the surface treatment liquid obtained in step (1) is stirred evenly, and the SC92ACR high carbon steel wire rod (diameter Φ5.5mm) that has undergone mechanical peeling, pickling (transferring through a 90g / L hydrochloric acid aqueous solution at 70℃ for 4s) and water washing (high pressure water rinsing) is transferred through the surface treatment liquid at a transfer speed of 0.4m / s. The wire rod passes through the surface treatment liquid for 7s (the surface treatment liquid is sufficient).

[0089] (3) Wax spraying for fixing

[0090] Polyethylene wax with a melting point range of 110℃~120℃ is fully melted at 200℃ and then sprayed onto the surface of the wire rod treated in step (2) through an atomizing nozzle at room temperature. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length. The three nozzles are evenly arranged around the circumference of the wire rod with the length direction of the wire rod as the central axis. The spray direction of each nozzle is perpendicular to the length direction of the wire rod and sprays at an atomizing pressure of 0.7MPa, thereby forming an atomization zone on the transport path of the wire rod, so that a polyethylene wax film of about 320μm thick is deposited on the surface of the wire rod that has been transported.

[0091] After the above-mentioned spraying, the wire rods are transferred into the drying room and left to stand at 103°C for 180 minutes.

[0092] The wire rod that underwent surface treatment as described in Comparative Example 3 was fed into a straight-line continuous wire drawing machine for cold drawing, following the same procedure as above. Cooling water was used to control the drum temperature of the wire drawing machine to below 67°C. The compression angle of the wire drawing die was 8°, the sizing strip length was 5mm, the drawing speed was 1.1m / s, the single-pass compression rate was 10%, and the number of drawing passes was 13. Finally, a steel cord with a diameter of 0.25mm was drawn. The resulting steel cord was polished to remove any residual lubricating components from the surface.

[0093] The steel cords obtained from the above embodiments and comparative embodiments were inspected for appearance and surface corrosion using an optical microscope. The specific results are shown in Table 1.

[0094] Table 1

[0095]

[0096] In the table above, the detection method for "surface corrosion degree" is as follows: On the steel cords processed in each embodiment and comparative embodiment, a length of 30cm is taken as a steel cord sample. After the oxide scale is removed by sanding the surface of the steel cord sample with fine sandpaper, the depth of the rust pits on the steel body is observed and measured using an optical microscope. For each sample, the depth of the 10 deepest rust pits is measured, and the average value is taken as the measurement result. The smaller the depth of the rust pit, the smaller the degree of corrosion.

[0097] As shown in Table 1, Comparative Example 1, due to the conventional operation of "treating the wire rod with borosilicate solution first and then carrying dry lubricating powder", had a limited amount of lubricating powder that could adhere to the wire rod due to adhesion issues. Therefore, during subsequent multiple drawing processes, the surface of the steel wire was eventually worn due to limited lubrication. Comparative Example 2, without using a polyethylene wax film coating, heated and dried the lubricating components on the surface of the wire rod. During the drying process, a large amount of lubricating powder lost its stickiness and fell off the wire rod, resulting in insufficient lubrication and wear on the surface of the steel wire during subsequent multiple drawing processes. Although Comparative Example 3 ensured the amount of lubricating powder used during drawing, the excessive thickness of the polyethylene wax coating prevented the formation of effective pore distribution during the deposition and cooling process of the polyethylene wax on the surface of the wire rod. This prevented the moisture in the lubricating components inside from effectively dissipating, ultimately leading to steel wire corrosion.

[0098] In Examples 1 to 3, not only is a significant amount of lubricating material retained during the drawing process, reducing wear on the wire surface during the drawing operation, but the degree of corrosion on the wire surface is not effectively increased due to the increased amount of lubricating material adhering to the wire surface by wetting.

Claims

1. A surface treatment process for steel cord wire rod before drawing, characterized in that: The surface treatment process is as follows: (1) Preparation of surface treatment solution The lubricating powder is fully dispersed in the borate solution at a concentration of 200-500 g / L to form a suspension, which is used as the surface treatment solution. (2) Surface coating The surface treatment liquid obtained in step (1) is used to coat the pretreated wire rod surface; (3) Wax spraying for fixing After melting polyethylene wax with a melting point of 110°C or higher, it is sprayed onto the surface of the wire rod treated in step (2) at room temperature to form a polyethylene wax film with a thickness of 50 to 300 μm, and then heated and dried at 100°C to 110°C.

2. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: The boronizing solution mentioned in step (1) is an aqueous solution of Na2B4O7 with a mass concentration of 15% to 20%.

3. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: The lubricating powder mentioned in step (1) is sodium stearate.

4. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: The pretreatment described in step (2) includes mechanical peeling, acid washing, and water washing in sequence.

5. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: In step (2), the wire rod is transferred through the surface treatment liquid obtained in step (1), and the transfer time of the wire rod in the surface treatment liquid is 5 to 10 seconds.

6. The surface treatment process before drawing steel cord wire rod as described in claim 5, characterized in that: In step (2), the transmission speed of the wire rod is 0.2 to 1 m / s.

7. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: In step (3), after the polyethylene wax is melted, it is sprayed onto the surface of the wire rod through a nozzle. There are three nozzles in total. The wire rod is transported forward in a straight line along its own length direction. The three nozzles are evenly arranged around the wire rod with the length direction of the wire rod as the central axis. The spraying direction of each nozzle is perpendicular to the length direction of the wire rod and aligned with the wire rod.

8. The surface treatment process before drawing steel cord wire rod as described in claim 1, characterized in that: In step (3), the polyethylene wax has a melting point of 110℃~120℃. The polyethylene wax is fully melted at 180℃~200℃ before spraying.

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