Rope forming process of 2*0. 32 UT structural steel cord

Abstract

The invention discloses a rope forming process of a 2 * 0.32 UT structural steel cord. The rope forming process comprises the following steps: (1) drawing a 92C wire rod with the diameter of 5.5 mm as a raw material to obtain a medium-drawn steel wire with the diameter of 2.0-2.2 mm; (2) quenching the obtained medium-drawn steel wire through AQ liquid to form a structure form of sorbite and a small amount of coarse lamellar pearlite; (3) the steel wire is sequentially subjected to acid pickling and alloy plating, and then passes through a medium-frequency diffusion furnace, so that copper atoms and zinc atoms are mutually diffused to form a brass-plated alloy layer; (4) the obtained brass-plated steel wire is continuously subjected to multi-pass drawing, and wet-drawn monofilaments with the diameter ranging from 0.315 mm to 0.325 mm are obtained; and (5) the wet-drawn monofilaments are subjected to doubling and cord thread forming through a double twisting machine and an outer winding machine according to a certain structure, arrangement and twisting requirements. According to the invention, the existing belted layer structure such as 2 + 2x0.25 HT is replaced at equal strength, the use amount of steel cords and sizing materials is reduced, and the light weight of the tire is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of steel cord, and particularly to a rope-making process for 2x0.32UT structure steel cord. Background Art

[0002] With the continuous development of the transportation industry, automobile tire technology has also undergone remarkable evolution, gradually moving towards the direction of lightweight, high strength, low rolling resistance and high durability. As a key component in the tire structure, steel cord plays an indispensable role in ensuring tire performance, and its quality and characteristics directly affect the overall performance of the tire. Modern automobile tire manufacturers strive to meet strict customer standards while achieving the tire weight reduction goal by optimizing the application of steel cord, and at the same time reducing the rolling resistance, which not only helps to improve the fuel efficiency of the vehicle, but also has a positive impact on reducing carbon emissions.

[0003] The steel cord used in the belt layer of current market PCR (radial) tires, such as specifications like 2+2x0.25HT, gradually shows certain limitations in actual applications. Due to their inherent strength limitations, these specifications of steel cord have to increase the wire density to make up for the insufficient strength on the premise of ensuring that the tire reaches the required breaking force. This means that more steel cord needs to be arranged inside the tire to maintain the same tensile strength standard, which inevitably increases the overall weight of the tire and is not conducive to the lightweight of the tire. Summary of the Invention

[0004] The purpose of the present invention is to provide a rope-making process for 2x0.32UT structure steel cord, which can replace the existing belt layer structure such as 2+2x0.25HT with equal strength, reduce the usage of steel cord and rubber compound, and achieve the lightweight of the tire.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a rope-making process for 2x0.32UT structure steel cord: (1) Using a 92C wire rod with a diameter of 5.5mm as the raw material for drawing to obtain an intermediate-drawn wire with a diameter of 2.0 - 2.2mm; (2) Quenching the above-obtained intermediate-drawn wire with AQ liquid to form a microstructure of sorbite and a small amount of coarse lamellar pearlite; (3) Pickling and alloy plating the above wire in sequence, and then passing it through an intermediate frequency diffusion furnace to make copper and zinc atoms diffuse into each other to form a brass alloy plating layer; (4) Continuously drawing the obtained brass-plated wire in multiple passes to obtain a wet-drawn single wire with a diameter of 0.315 - 0.325mm; (5) According to certain structure, arrangement and twisting requirements, the above wet-drawn single wires are used for wire merging and cord forming through a double-twisting machine and an outer winding machine.

[0006] A further improved solution of the present invention is that the composition of the 92C wire rod, by mass percentage, includes: C: 0.88% - 0.95%, Si: 0.15% - 0.25%, Mn: 0.25% - 0.55%, P: ≤0.025%, S: ≤0.020%, Cr: 0.10 - 0.30%, Ni: ≤0.05%, Cu: ≤0.05%, Al: ≤0.003%, and the balance is Fe and unavoidable impurities.

[0007] A further improved solution of the present invention is that the above-mentioned 92C wire rod is payed off by a C-type hook. After the surface scale of the wire rod is removed by a descaling box, pickling, water rinsing, boron coating are carried out in sequence. Using soap powder as the drawing environment, the wire rod is drawn once through a wire drawing die by a servo direct drive wire drawing machine to obtain a large-drawn wire of Φ3.25mm.

[0008] A further improved solution of the present invention is that it is drawn a second time through a wire drawing die to obtain an intermediate-drawn wire with a diameter of 2.1mm and a stable surface residual coating, and then it is wound onto a take-up frame.

[0009] A further improved solution of the present invention is that the above-mentioned intermediate-drawn wire with a diameter of 2.1mm is degreased, the heating furnace is heated up, AQ quenching, water cooling, pickling, water rinsing, copper plating, water rinsing, zinc plating, water rinsing, hot water washing, intermediate frequency diffusion, water cooling, phosphoric acid pickling, water rinsing, soap dipping are carried out in sequence in the alloying process, and finally it is wound onto a spool to obtain a brass-plated wire with a diameter of 2.1 mm.

[0010] A further improved solution of the present invention is that a wet drawing process is adopted to draw the brass-plated wire with a diameter of 2.1 mm for 25 passes: During the 1st to 12th passes of drawing, the compression ratio of the wire in each pass ≥14.5%, and the wire diameter > 0.80mm; During the 13th to 19th passes of drawing, 14% ≤ the compression ratio of the wire in each pass ≤ 14.5%, and 0.48 ≤ the wire diameter ≤ 0.80mm; During the 20th to 24th passes of drawing, 13.8% ≤ the compression ratio of the wire in each pass < 14.2%, and 0.330 ≤ the wire diameter < 0.48mm; During the 25th pass of drawing, 0.315 ≤ the wire diameter ≤ 0.325mm.

[0011] A further improved solution of the present invention is that during the 20th to 24th passes, double die drawing is adopted. The die diameter of the auxiliary die is one half of the sum of the die diameter of the previous pass and the die diameter of this pass, and the auxiliary die is located between the die of the previous pass and the die of this pass.

[0012] A further improved solution of the present invention is that an auxiliary die is arranged between the 24th pass and the 25th pass, and the compression ratio of the auxiliary die is 1 - (diameter of the auxiliary die² / diameter of the die in the 24th pass²).

[0013] A further improved solution of the present invention is that the compression ratio of the steel wire in the 1st and 2nd passes < the compression ratio of the driven wheel. The compression ratio in the 1st pass is 5.0 ± 1.0%, and the compression ratio of the steel wire in the 2nd pass is controlled to be 10.0 ± 1.0%; The compression ratio of the steel wire in the 3rd - 5th passes > the compression ratio of the driven wheel. The compression ratio of the steel wire increases step by step in the 3rd - 5th passes, and the compression ratio in the 5th pass reaches the maximum value. The compression ratio in the 3rd pass is controlled to be 14.0 ± 1.0%, the compression ratio in the 4th pass is controlled to be 16.0 ± 1.0%, and the compression ratio in the 5th pass is controlled to be 17 ± 0.5%; The compression ratio of the steel wire in the 6th - 12th passes > the compression ratio of the driven wheel. After the maximum compression ratio in the 5th pass, the compression ratio of the steel wire should decrease step by step, and the compression ratio in each pass ≥ 14.5%.

[0014] A further improved solution of the present invention is that 2 pieces of the above - mentioned wet - drawn single wires are used for the steel cord of 2x0.32UT specification. After the 2 single wires come out from the corresponding spools, they first pass through a tension swing rod to stabilize the tension of the single wires, and then the 2 single wires pass through the rope - passing holes and the compression die, and are twisted into a rope under the action of a double - twister.

[0015] The beneficial effects of the present invention are as follows: The linear density of the 2x0.32UT of the present invention is significantly reduced, and the breaking tensile force / linear density is increased by 23% compared with 2 + 2x0.25HT. Thus, the cord quality index is significantly reduced, the weight of the tire is reduced, the tire manufacturing cost is reduced, and the fatigue resistance is improved, which is beneficial to the lightweight of the tire.

[0016] Through the double - die process, the present invention divides the compression ratio of the steel wire in this pass into two, and reduces the compression ratio of this pass on the premise of ensuring that the steel wire is fully drawn.

[0017] By setting an auxiliary die, the die pit of the auxiliary die is located before the final pass, reducing the compression ratio of the steel wire in the final pass and reducing the risk of wet - drawing wire breakage. Description of the Drawings

[0018] Figure 1 It is the data table of the die chain passes of the present invention.

[0019] Figure 2 It is the compression ratio curve of the die chain of the present invention.

[0020] Figure 3 It is the slip curve of the die chain of the present invention.

[0021] Figure 4It is a schematic cross-sectional view of the 2x0.32UT structural steel cord of the present invention. Detailed implementation manners

[0022] The present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments. Embodiment

[0023] Combined with Figures 1 to 4 It can be known that the cord-making process of a 2x0.32UT structural steel cord is as follows: (1) The 92C wire rod with a diameter of 5.5 mm is used as the raw material for drawing to obtain medium-drawn steel wires with a diameter of 2.0 - 2.2 mm; (2) The medium-drawn steel wires obtained above are quenched through AQ liquid to form a microstructure of sorbite and a small amount of coarse lamellar pearlite; (3) The above steel wires are pickled, alloy-plated in sequence, and then passed through an intermediate-frequency diffusion furnace to enable the mutual diffusion of copper and zinc atoms to form a brass-plated alloy layer, and the percentage of copper content in the brass-plated alloy layer is 61% - 66%; (4) The obtained brass-plated steel wires are continuously drawn in multiple passes to obtain wet-drawn single wires with a diameter of 0.315 - 0.325 mm; (5) The above wet-drawn single wires are combined and cord-formed through a double-twisting machine and an outer winding machine according to certain structure, arrangement, and twisting requirements.

[0024] The composition of the 92C wire rod, by mass percentage, includes: C: 0.88% - 0.95%, Si: 0.15% - 0.25%, Mn: 0.25% - 0.55%, P: ≤0.025%, S: ≤0.020%, Cr: 0.10 - 0.30%, Ni: ≤0.05%, Cu: ≤0.05%, Al: ≤0.003%, and the balance is Fe and unavoidable impurities.

[0025] Preferably, the composition of the wire rod, by mass percentage, includes: C: 0.93%, Si: 0.19%, Mn: 0.34%, P: 0.008%, S: 0.005%, Cr: 0.17%, Ni: 0.02%, Cu: 0.02%, Al: 0.001%.

[0026] Preferably, in step (1), the above 92C wire rod is payed off through a C-type hook. After the wire rod removes the surface scale in the descaling box, it is pickled, water-rinsed, boron-coated in sequence, and the servo direct-drive wire drawing machine uses soap powder as the drawing environment and is drawn once through a wire drawing die to obtain large-drawn steel wires with a diameter of Φ3.25 mm, and then drawn a second time through a wire drawing die to obtain medium-drawn steel wires with a diameter of 2.1 mm and a stable surface residual coating, and then wound onto a take-up rack.

[0027] Preferably, in steps (2) and (3), the above medium-drawn steel wire with a diameter of 2.1 mm is subjected to degreasing, heating furnace temperature rise, AQ quenching, water cooling, pickling, water rinsing, copper plating, water rinsing, zinc plating, water rinsing, hot water washing, intermediate frequency diffusion, water cooling, phosphoric acid pickling, water rinsing, soap dipping, and finally coiling onto a spool in the alloy process to obtain a brass-plated steel wire with a diameter of 2.1 mm. The thickness of the brass coating on the steel wire surface is 2 - 3 μm, the coating weight is 4 ± 0.3 g / kg, the percentage of copper content in the coating is 63.5 ± 2.5%, and the tensile strength is 1320 ± 20 N / mm 2 。

[0028] Preferably, in step (4), the wet drawing equipment draws through a 25-pass die chain (2.040 - 1.930 - 1.788 - 1.640 - 1.495 - 1.365 - 1.248 - 1.143 - 1.050 - 0.967 - 0.892 - 0.825 - 0.763 - 0.706 - 0.654 - 0.606 - 0.562 - 0.521 - 0.483 - double die 0.465 / 0.448 - double die 0.432 / 0.416 - double die 0.401 / 0.386 - double die 0.372 / 0.358 - double die 0.345 / 0.332 - auxiliary die 0.326 - 0.322) using the wet drawing process to perform 25 passes of drawing on the brass-plated steel wire with a diameter of 2.1 mm: During the 1st to 12th passes of drawing, the compression ratio of the steel wire in each pass is ≥ 14.5%, and the diameter of the steel wire > 0.80 mm; During the 13th to 19th passes of drawing, 14% ≤ the compression ratio of the steel wire in each pass ≤ 14.5%, and 0.48 ≤ the diameter of the steel wire ≤ 0.80 mm; During the 20th to 24th passes of drawing, 13.8% ≤ the compression ratio of the steel wire in each pass < 14.2%, and 0.330 ≤ the diameter of the steel wire < 0.48 mm; to reduce the risk of wire scratching caused by stick-slip; During the 25th pass of drawing, 0.315 ≤ the diameter of the steel wire ≤ 0.325 mm.

[0029] The specific pass data table is as follows:

[0030] The diameter of the wire gradually decreases and the tensile strength gradually increases from the 13th to the 24th pass, resulting in a relatively high die wear in the 13th - 24th pass. The number of winding turns is reduced to 1.5 turns to increase the service life of the wire drawing die, but the drawing force increases significantly. By achieving: the compression ratio of the driving wheel 13% = the compression ratio of the driven wheel 13%, the friction force is increased to offset part of the drawing force, so as to reduce the risk of wire breakage. The change of the wire compression ratio in the 13th - 19th pass shows the characteristics of overall decreasing and local fine-tuning. During the overall process of following a stepped decrease to 14.0%, the compression ratio of individual passes (such as between adjacent passes) is allowed to maintain a plateau value or have a technical callback, but the stability of the macroscopic downward trend is ensured through the process control system.

[0031] The compression ratio of the wire is controlled by the diameter of the die chain (Dies, wire drawing die). For example: the compression ratio of the wire in the 1st pass is: 1 - (the diameter of the die chain in the 1st pass)² / (the diameter of the wire)²; the compression ratio of the wire in the 2nd pass is: 1 - (the diameter of the die chain in the 2nd pass)² / (the diameter of the die chain in the 1st pass)². After the wire is drawn through the die chain in the 1st pass, the diameter of the wire changes from 2.10 mm to 2.04 mm. After the wire is drawn through the 2nd die chain, the diameter of the wire changes from 2.04 mm to 1.93 mm.

[0032] Double die drawing is adopted in the 20th - 24th pass. The die diameter of the auxiliary die is one-half of the sum of the die diameter of the previous pass and the die diameter of this pass, and the auxiliary die is located between the die of the previous pass and the die of this pass. In the 20th - 24th pass, there are 2 die pits in a single pass, and two wire drawing dies can be used to form a double die process, dividing the compression ratio of the wire in this pass into two parts. On the premise of ensuring that the wire is fully drawn, the compression ratio of this pass is reduced.

[0033] An auxiliary die is set between the 24th pass and the 25th pass. The compression ratio of the auxiliary die is 1 - (the diameter of the auxiliary die)² / (the diameter of the die in the 24th pass)². The diameter of the auxiliary die is smaller than the diameter of the previous pass and larger than the diameter of the next pass. Preferably, 0.325 < the diameter of the auxiliary die ≤ 0.330.

[0034] The die pit of the auxiliary die is located before the final pass. The main purpose is to reduce the compression ratio of the wire in the final pass and reduce the risk of wet drawing wire breakage. The 25th pass is the final finished product pass, and the tensile strength of the wire is the largest. When the compression ratio of the finished product pass 5.9% > the compression ratio of the driven wheel 4.5%, the wire breakage rate before the final pass is high. Adding 1 auxiliary die before the final pass can reduce the compression ratio to 2.4%.

[0035] Compression ratio of the auxiliary die: 1 - (diameter of the auxiliary die)² / (diameter of the die at the 24th pass)² = 1 - 0.326² / 0.332² = 3.6%; Compression ratio of the last pass: 1 - (diameter of the finished product die)² / (diameter of the auxiliary die)² = 1 - 0.322² / 0.326² = 2.4%. Compression ratio of the last pass before adding the auxiliary die: 1 - (diameter of the finished product die)² / (diameter of the die at the 24th pass)² = 1 - 0.322² / 0.332² = 5.9%.

[0036] Compression ratio of the 25th pass: 1 - 0.322² / 0.332² = 5.93% > compression ratio of the driven wheel 4.5% (since it is the last pass and the driving wheel does not need to provide power anymore, so there is no compression ratio for the driving wheel, and the driven wheel is used to provide power). Since it is the finished product wire, P = F / S. After the wire undergoes plastic deformation, the F force will increase, the diameter of the wire becomes smaller, so the area of the wire decreases, and thus P increases. It can be understood that the tensile strength is the largest at this time. If the wire is directly drawn, the wire will break. Therefore, the wire is drawn in 2 steps, an auxiliary die is added to share the compression ratio of the last pass, and the wire is deformed in 2 steps, thereby reducing the wire breakage rate.

[0037] Furthermore, when drawing with the wire drawing die in the 1st to 12th passes, the compression ratio shows a trend of increasing first and then decreasing. Specifically as follows: Compression ratio of the wire in the 1st and 2nd passes < compression ratio of the driven wheel. Compression ratio of the 1st pass is 5.0 ± 1.0% to ensure the lubrication effect at the initial stage of wire drawing. Compression ratio of the wire in the 2nd pass is controlled at 10.0 ± 1.0% to reduce the risk of hardening and peeling of the alloy layer of the brass-plated wire; Compression ratio of the wire in the 3rd to 5th passes > compression ratio of the driven wheel. The compression ratio of the wire in the 3rd to 5th passes increases gradually. The compression ratio of the 5th pass reaches the maximum value. Compression ratio of the 3rd pass is controlled at 14.0 ± 1.0%, compression ratio of the 4th pass is controlled at 16.0 ± 1.0%, and compression ratio of the 5th pass is controlled at 17 ± 0.5% to make the wire deform uniformly inside; Compression ratio of the wire in the 6th to 12th passes > compression ratio of the driven wheel. After the maximum compression ratio of the 5th pass, the compression ratio of the wire should decrease gradually, and the compression ratio of each pass ≥ 14.5% to reduce the risk of wire scratching caused by stick-slip.

[0038] In the 1st to 12th passes, the diameter of the wire is relatively large, and the slip rate generated during the contact with the tower wheel is relatively large. On the premise of ensuring that the wire is fully drawn, the number of winding turns of the wire is increased to 3.5 turns, which can reduce the repeated forward and backward movement like micro-vibration when the wire passes through the wire drawing die and avoid wire scratching; The compression ratio of the driving wheel is controlled at 16% and the compression ratio of the driven wheel is controlled at 13%: make the driven wheel rotate faster than the driving wheel, reduce the transmission speed ratio, and reduce the friction between the wire and the wire drawing die and the tower wheel.

[0039] Preferably, in step (5), two such wet-drawn single filaments are used for a steel cord of 2x0.32UT specification. After the two single filaments come out of the corresponding spools, they first pass through a tension pendulum to stabilize the tension of the single filaments, and then the two single filaments pass through a rope threading hole and a die, and are twisted into a rope under the action of a double twister.

[0040] The design principle of the steel cord with a 2x0.32UT structure of the present invention is equal-strength substitution. The performance parameters of the steel cord of the present invention are compared with those of the steel cord of the existing PCR tire belt layer structure as follows:

[0041] It can be seen from the table that compared with the steel cord of the existing PCR tire belt layer structure, while keeping the breaking force unchanged, the linear density of 2x0.32UT in this embodiment is significantly reduced, and the ratio of breaking tensile force / linear density is increased by 23% compared with 2+2x0.25HT. Therefore, the cord quality index is significantly reduced, the tire weight is reduced, the tire manufacturing cost is reduced, and the fatigue resistance is improved, which is beneficial to the lightweight of the tire.

[0042] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A rope-forming process for 2x0.32UT structural steel cord, characterized by: (1) Drawing 92C wire rod with a diameter of 5.5 mm as raw material to obtain medium-drawn steel wire with a diameter of 2.0~2.2 mm; (2) quenching the dry drawn steel wire obtained above by AQ liquid to form a microstructure of troostite and a small amount of coarse lamellar pearlite; (3) The steel wire is pickled and alloy plated in sequence, and then passed through a medium frequency diffusion furnace to allow copper and zinc atoms to diffuse into each other to form a brass alloy layer; (4) continuously drawing the obtained brass-plated steel wire for multiple passes to obtain a wet-drawn single wire with a diameter of 0.315-0.325 mm; (5) The wet-drawn monofilaments are paralleled and formed into cords through a double twisting machine and an outer winding machine according to certain structural, arrangement and twisting requirements.

2. The process for forming a 2x0.32UT structural steel cord according to claim 1, characterized in that: The composition of 92C wire rod, in terms of mass percentage, includes: C: 0.88%~0.95%, Si: 0.15%~0.25%, Mn: 0.25%~0.55%, P: ≤0.025%, S: ≤0.020%, Cr: 0.10~0.30%, Ni: ≤0.05%, Cu: ≤0.05%, Al: ≤0.003%, and the balance is Fe and unavoidable impurities.

3. The rope-making process of a 2x0.32UT structural steel cord according to claim 1, characterized in that: The 92C wire rod is paid out by a C-hook. After passing through a descaling box to remove the surface oxide scale, the wire rod is pickled, rinsed with water, and boron coated. A servo direct-drive wire drawing machine uses soap powder as the drawing environment and draws once through a wire drawing die to obtain a Φ3.25mm large drawn steel wire.

4. The rope-making process of a 2x0.32UT structural steel cord according to claim 3, characterized in that: The wire is drawn again through the wire drawing die to obtain a medium-drawn steel wire with a diameter of 2.1 mm and a stable residual coating on the surface, and then the wire is taken up onto the take-up frame.

5. The 2x0.32UT structural steel cord rope-making process according to claim 4, characterized in that: The above-mentioned medium-drawn steel wire with a diameter of 2.1 mm is degreased, heated in a heating furnace, AQ quenched, water-cooled, pickled, rinsed with water, copper-plated, water-rinsed, galvanized, rinsed with water, washed with hot water, medium-frequency diffused, water-cooled, washed with phosphoric acid, rinsed with water, soap-soaked, and finally wound onto an I-shaped wheel in the alloy process to obtain a brass-plated steel wire with a diameter of 2.1 mm.

6. The process for forming a 2x0.32UT structural steel cord according to claim 5, characterized in that: Using the wet drawing process, 25 passes of drawing are performed on a 2.1 mm diameter brass-plated steel wire: During the 1st to 12th drawing passes, the wire compression rate of each pass is ≥14.5%, and the wire diameter is >0.80mm; During the 13th to 19th drawing, the wire compression rate of each pass is 14%≤14.5%, and the wire diameter is 0.48≤0.80mm; During the 20th to 24th drawing, the wire compression rate of each pass is 13.8%≤<14.2%, and the wire diameter is 0.330≤<0.48mm; During the 25th drawing pass, the wire diameter is 0.315≤≤0.325mm.

7. A 2x0.32UT structural steel cord rope-making process according to claim 6, characterized in that: The 20th to 24th passes are drawn by double die, the die diameter of the sub-die is half of the sum of the die diameter of the previous pass and the die diameter of the current pass, and the sub-die is located between the previous die and the current die.

8. A 2x0.32UT structural steel cord rope-making process according to claim 6 or 7, characterized in that: An auxiliary die is set between the 24th and 25th passes, and the compression rate of the auxiliary die is 1-auxiliary die diameter² / 24th pass die diameter².

9. The process for forming a 2x0.32UT structural steel cord according to claim 6, characterized in that: The compression rate of the steel wire in the first and second passes is less than the compression rate of the driven wheel. The compression rate of the first pass is 5.0±1.0%, and the compression rate of the steel wire in the second pass is controlled to be 10.0±1.0%; The compression rate of the steel wire in the 3rd to 5th passes is greater than that of the driven wheel. The compression rate of the steel wire increases step by step in the 3rd to 5th passes, and reaches the maximum value in the 5th pass. The compression rate of the 3rd pass is controlled to be 14.0±1.0%, the compression rate of the 4th pass is controlled to be 16.0±1.0%, and the compression rate of the 5th pass is controlled to be 17±0.5%; The compression rate of the steel wire in the 6th to 12th passes is greater than the compression rate of the driven wheel. After the steel wire has passed the maximum compression rate in the 5th pass, the compression rate of the steel wire shall decrease step by step, and the compression rate of each pass shall be ≥14.5%.

10. A 2x0.32UT structural steel cord rope-making process according to claim 1 or 6, characterized in that: The two wet-drawn monofilaments are used for 2x0.32UT steel cord. After coming out of the corresponding I-shaped wheels, the two monofilaments first pass through a tension swing rod to stabilize the tension of the monofilaments. Then, the two monofilaments pass through the rope threading hole and the die, and are twisted into ropes under the action of a double twisting machine.

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