Method for controlling intermittent lugs in tire cord steel rolling process

Abstract

The invention discloses a method for controlling discontinuous lugs in a tire cord steel rolling process. The method comprises the following steps: smelting in a converter; heating the casting blank; performing three-section water cooling on the rolled piece; rolling is conducted; reducing and sizing; and conventionally carrying out subsequent procedures. Under the condition that existing equipment and working procedures do not need to be transformed, the problem of generation of the discontinuous lugs of the tire cord steel can be effectively solved, the generation frequency of the discontinuous lugs of the tire cord steel produced in the working procedure is reduced from original 10.5 times per kiloton of steel to 0.2 times per kiloton of steel, and relevant standards and user requirements can be completely met.

Description

Technical Field

[0001] The present invention relates to a method for preparing cord steel, and more specifically to a method for controlling intermittent ears during the rolling process of cord steel. Background Art

[0002] The series of wire rod for cord steel is one of the main raw materials for producing the skeleton of automobile tire cords, the broadest product among rubber skeleton materials, and also the product with the greatest production difficulty in metal products. It is widely used in fields such as car tires, light truck tires, heavy-duty truck tires, industrial machinery vehicle tires, aircraft tires, and other rubber product skeleton materials. Cord steel is an industrial material made of high-quality carbon steel with a brass coating on the surface and is a thin-specification wire strand or rope with special uses. The radial tire made with cord steel as the reinforcing material has the characteristics of long service life, high driving speed, puncture resistance, good elasticity, safety and comfort, and fuel savings.

[0003] The process flow of cord steel wire rod (for making tire radials): pretreatment and rough drawing → inspection → intermediate heat treatment → medium wire drawing → heat treatment and electroplating → wet drawing → stranding into ropes → finished wire.

[0004] Due to the complex deep processing process of the wire rod and multiple drawing operations, the rough and medium drawing are carried out on straight-through wire drawing machines, and the speed of the rough drawing machine reaches 15 m / s. Due to the fast drawing speed, the wire rod has intermittent ears (commonly known as the defect of "airplane with wings"), which will directly damage the dies of the rough drawing machine, not only damaging the rough drawing die equipment but also causing the process to stop, seriously affecting the user experience. Therefore, cord steel is not allowed to have intermittent ear defects.

[0005] During 2020 - 2021, the cord steel produced by Wugang High-Speed Wire Rod had 3 cases where the intermediate intermittent ears caused damage to the rough drawing dies when used by Jiangsu Xingda Cord Steel Co., Ltd., seriously affecting the use experience of Wugang High-Speed Wire Rod cord steel in Jiangsu Xingda Cord Steel Co., Ltd.

[0006] After retrieval:

[0007] The literature with the Chinese patent publication number CN111687221 discloses "A Bar and Wire Rod Export Guide". It includes: a guiding member, within which a guiding hole is provided, and the inlet of the guiding hole communicates with the roll hole; two guiding rollers which form a micro-rolling hole, and the micro-rolling hole communicates with the outlet of the guiding hole; a support frame, on which both the guiding member and the guiding rollers are fixed. The bar and wire rod export guide in the present invention not only has a guiding hole but also a micro-rolling hole. The bar and wire rod rolled by the roll enters the guiding hole and steadily leaves the roll under the guiding action of the guiding hole. Immediately afterwards, the bar and wire rod will enter the micro-rolling hole, and the two guiding rollers clamp and straighten the shape of the bar and wire rod, and can eliminate the "ear" defect on the free spread surface. The bar and wire rod export guide in the present invention can not only accurately guide the bar and wire rod, but also clamp and straighten the shape of the bar and wire rod material, and eliminate the "ear" defect on the free spread surface. This literature does not mention relevant parameters such as the continuous casting of cord steel in a converter, RH vacuum treatment and casting into billets; the control of the billet heating temperature; the water tank cooling method; the control of the finish rolling size; the optimization of the reducing and sizing roll gap, etc.

[0008] The literature with the Chinese patent publication number CN214022594 discloses "A Rolling Mill Production Line for Producing Wire Rods with a Cross-sectional Circular Diameter of 5.5 mm", which includes a rough rolling mill set, a first flying shear, an intermediate rolling mill set, a first side loop, a pre-finishing mill set, a first water tank set, a third flying shear, a second side loop, a 10-stand finishing mill set, a second water tank set, a double-stand mini rolling mill, a third water tank set, pinch rolls, a wire laying head and an air-cooling roller table line arranged in sequence along the direction of the rolled piece; the double-stand mini rolling mill includes a twenty-ninth rolling mill stand and a thirtieth rolling mill stand arranged in sequence along the direction of the rolled piece. An inlet sliding guide is provided at the inlet of the twenty-ninth rolling mill stand, and an outlet sliding guide is provided at the outlet of the twenty-ninth rolling mill stand. One end of the inlet sliding guide facing the twenty-ninth rolling mill stand is plane conical, and the top surface and the bottom surface of the plane cone are inclined planes, and the length T of the inclined plane is 60 - 62 mm. This rolling mill production line can effectively reduce or even eliminate the probability of generating "airplane" materials. This literature does not mention relevant parameters such as the continuous casting of cord steel in a converter, RH vacuum treatment and casting into billets; the control of the billet heating temperature; the water tank cooling method; the control of the finish rolling size; the optimization of the reducing and sizing roll gap, etc. Summary of the Invention

[0009] The present invention aims to overcome the deficiencies existing in the prior art, such as the torsional movement of the rolled piece during the production of cord steel in the finishing rolling and reducing-sizing pass, which is caused by the changes in the spread and elongation of the rolled piece during the process control, resulting in intermittent ear defects in the reducing-sizing mill, etc. The present invention provides a control method for intermittent ears in the cord steel rolling process, which can effectively solve the generation of intermittent ears in cord steel without modifying the existing equipment and processes, reduce the incidence of intermittent ears in the production of cord steel in this process from the original 10.5 times per thousand tons of steel to no more than 0.2 times per thousand tons of steel, and can fully meet the relevant standards and user requirements.

[0010] Measures to achieve the above objectives:

[0011] A control method for intermittent ears in the cord steel rolling process, the steps of which are as follows:

[0012] 1) Smelt in a converter and cast into slabs after RH vacuum treatment;

[0013] 2) Heat the cast slabs, and during this period: control the temperatures of the head, middle, and tail sections of the cast slabs as follows:

[0014] The head is controlled at 1000 - 1020 °C, the middle is controlled at > 1020 to 1040 °C, and the tail is controlled at 1050 - 1070 °C;

[0015] 4) Perform three-stage water cooling on the rolled piece, and during this period:

[0016] Control the pressure of the cooling water entering the water tank in the first stage at 2.5 - 2.8 bar, do not set a cold section at the head, and open the first water tank in this section for cooling;

[0017] Control the pressure of the cooling water entering the water tank in the second stage at 2.0 - 2.5 bar, the length of the head cooling section in this section is 20 ± 0.5 m, the length of the tail cooling section is 5 ± 0.5 m, and open the first water tank in this section for cooling;

[0018] Control the pressure of the cooling water entering the water tank in the third stage at 0.4 - 0.8 bar, the length of the head cooling section in this section is 10 ± 0.5 m, the length of the tail cooling section is 0 - 1 m, and open the first water tank in this section for cooling;

[0019] 4) Perform rolling, and during this period, control the size at the exit of the finishing rolling at 37.2 - 37.5 mm 2 , the sky-earth size * the side sizes are in the range of: 7.05 - 7.15 mm * 6.45 - 6.65 mm; the opening degree of the rolling guide on the 32nd stand is controlled at 0.9 ± 0.02 mm;

[0020] 5) Perform reducing sizing. During this process, adjust the roll gaps of the 31st to 34th stands to: the roll gap of the 31st stand is adjusted to 1.3 ± 0.01 mm, the roll gap of the 32nd stand is adjusted to 1.0 ± 0.01 mm, the roll gap of the 33rd stand is adjusted to 1.4 ± 0.01 mm, and the roll gap of the 34th stand is adjusted to 1.4 ± 0.01 mm;

[0021] 6) Conduct subsequent processes conventionally.

[0022] Preferably: the temperatures of each section of the head, middle, and tail of the billet are controlled as follows: the head is controlled at 1000 - 1015 °C, the middle is controlled at 1025 to 1035 °C, and the tail is controlled at 1055 - 1065 °C.

[0023] It lies in that: the sky - earth dimension * side dimension: the sky - earth dimension refers to the diameter dimension between the upper roll ring and the lower roll ring of finish rolling; the side dimension refers to the diameter dimension of the rolled piece between the two sides of the finish rolling roll ring.

[0024] The functions and mechanisms of the main processes in the present invention

[0025] The reason for controlling the temperatures of each section of the head, middle, and tail of the cord - steel billet in the present invention is as follows:

[0026] The head is controlled at 1000 - 1020 °C, the middle is controlled at 1020 - 1040 °C, and the tail is controlled at 1050 - 1070 °C. This is because the cross - sectional dimensions of the cord - steel billet for high - speed wire are generally 151 mm * 165 mm * 12 m, and the rolling time for the whole billet is about 125 s. Due to the limitations of the rolling process, there is a natural temperature drop in the middle and tail of the billet on the holding roller table. If there is no temperature compensation in the heating furnace, the temperature differences of the head, middle, and tail will be large when entering the water tank after pre - finish rolling, which will cause changes in the spread and elongation of the rolled piece after entering the finish rolling and reducing sizing mills, resulting in intermittent ears in the middle and rear parts of the finished product.

[0027] The reason why the present invention controls the pressure of the cooling water entering the first water tank to be 2.5 - 2.8 bar, without a cold section at the head, and opens the first water tank in this section for cooling; controls the pressure of the cooling water entering the second water tank to be 2.0 - 2.5 bar, with the length of the head cooling section in this section being 20 ± 0.5 m and the length of the tail cooling section being 5 ± 0.5 m, and opens the first water tank in this section for cooling; controls the pressure of the cooling water entering the third water tank to be 0.4 - 0.8 bar, with the length of the head cooling section in this section being 10 ± 0.5 m and the length of the tail cooling section being 0 m, and opens the first water tank in this section for cooling; this is because the cross-sectional diameter of the red-hot steel in the first section is 20 mm * 20 mm, and high water pressure is used for cooling. By opening the first water tank in this section, the recovery time of the rolled piece after cooling is increased, the temperature difference between the surface temperature and the core temperature of the rolled piece entering the finish rolling is reduced. Since it passes through the flying shear before entering the finish rolling and at the same time ensures the cooling performance of the head steel, the high-temperature section of the first section is set to 0 m; the water pressure in the second section is reduced because at this time the cross-sectional dimensions of the finish rolling are only 7.05 - 7.15 mm * 6.45 - 6.65 mm. If the water pressure is too high, the rolled piece shakes severely after passing through the water tank and is prone to piling up steel in the finish rolling waste bin, and there is no flying shear after the finish rolling. The head high-temperature section is set to prevent piling up of steel with water penetration at the head. The water pressure in the third section is set low because the outlet size of the rolled piece in the reducing and sizing is only 5.5 ± 0.2 mm. To prevent piling up of steel in the reducing and sizing waste bin due to an increase in water pressure, the length of the head cooling section in this section is 20 ± 0.5 m to ensure that the high-temperature section of the head can be sheared cleanly when the steel is sheared in the rear area.

[0028] The reason why the present invention solidifies the finish rolling area and the finish rolling dimensions is that the finish rolling area corresponds to the optimization of the roll gap of the reducing and sizing mill; the top and bottom dimensions > the side dimensions because the law of minimum resistance is conducive to the biting of the 31st rolling mill stand and the guiding of the rolled piece by the guide device of the 32nd rolling mill stand. Moreover, it is to prevent the increase in the tail size caused by the loss of tension at the tail after the rolled piece detaches from the finish rolling mill, resulting in intermittent ears caused by the change in the second flow rate of the rolled piece in the reducing and sizing mill.

[0029] The reason why the present invention controls the opening degree of the guide device of the 32nd rolling mill stand to be 0.9 ± 0.02 mm is that the inlet guide device guides the trend of the billet. From actual production, if the opening degree of the guide device is too small, steel will pile up with a tail in the guide device, and the guide device of the 32nd rolling mill stand is not durable. If the opening degree of the guide device is too large, the guiding effect of the guide device on the billet fails, resulting in the deviation of the rolled piece, the phenomenon of the head hitting the 32nd rolling mill stand and getting stuck, and the degree of freedom of the rolled piece in the guide device becomes larger, and the rolled piece twists to cause intermittent ears.

[0030] The reason why the roll gap of the 31st stand is adjusted to 1.3 ± 0.01 mm, the roll gap of the 32nd stand is adjusted to 1.0 ± 0.01 mm, the roll gap of the 33rd stand is adjusted to 1.4 ± 0.01 mm, and the roll gap of the 34th stand is adjusted to 1.4 ± 0.01 mm minus the sizing roll gap is that through the simulation of CAD software, it is found that when the width-height ratio > 2.4 when entering the 32nd stand in the sizing process, the rolled piece is stable. With the cooperation of the finish rolling area and size control, the jitter of the rolled piece in the sizing mill is stable, and the size of the whole length is stable.

[0031] Compared with the prior art, without the need to transform the existing equipment and processes, the present invention can effectively solve the generation of intermittent fins in cord steel, reducing the occurrence frequency of intermittent fins in the cord steel produced in this process from the original 10.5 times per thousand tons of steel to no more than 0.2 times per thousand tons of steel, and can fully meet the relevant standards and user requirements. Specific embodiments

[0032] The present invention is described in detail below:

[0033] Example 1

[0034] A control method for intermittent fins during the rolling process of cord steel, the steps of which are as follows:

[0035] 1) Converter smelting, casting into billets after RH vacuum treatment;

[0036] 2) Heating the billets, during which: control the temperatures of the head, middle and tail sections of the billets as follows:

[0037] The head is controlled at 1002 °C, the middle is controlled at 1026 °C, and the tail is controlled at 1063 °C;

[0038] 3) Three-stage water cooling of the billets, during which:

[0039] Control the pressure of the cooling water entering the water tank in the first stage at 2.68 bar, without a cold section at the head, and open the first water tank in this section for cooling;

[0040] Control the pressure of the cooling water entering the water tank in the second stage at 2.05 bar, the length of the head cooling section in this section is 20.5 m, the length of the tail cooling section is 4.5 m, and open the first water tank in this section for cooling;

[0041] Control the pressure of the cooling water entering the water tank in the third stage at 0.52 bar, the length of the head cooling section in this section is 10 m, the length of the tail cooling section is 0.2 m, and open the first water tank in this section for cooling;

[0042] 4) Rolling, during which, control the finish rolling exit size at 37.2 mm 2 , the top-bottom size * the side sizes are:

[0043] 7.08mm * 6.45mm; The opening of the rolling guide at the 32nd stand is controlled at 0.89mm;

[0044] 5) Sizing and finishing rolling, during which the roll gaps of the 31st to 34th stands are adjusted to: the roll gap of the 31st stand is adjusted to 1.31mm, the roll gap of the 32nd stand is adjusted to 1.0mm, the roll gap of the 33rd stand is adjusted to 1.39mm, and the roll gap of the 34th stand is adjusted to 1.41mm;

[0045] 6) Conduct subsequent processes conventionally.

[0046] According to the statistics of downstream customers' use: In this embodiment, 24,651 tons of finished product specification of wire rod steel with a diameter of ф5.5mm are produced, and the occurrence times of intermittent fins of the wire rod steel are 0 times.

[0047] Example 2

[0048] A control method for intermittent fins during the rolling process of wire rod steel, the steps are as follows:

[0049] 1) Converter smelting, casting into billets after RH vacuum treatment;

[0050] 2) Heating the billets, during which: control the temperatures of the head, middle, and tail sections of the billets as follows:

[0051] The head is controlled at 1005°C, the middle is controlled at 1028°C, and the tail is controlled at 1067°C;

[0052] 3) Three-stage water cooling of the billets, during which:

[0053] Control the pressure of the cooling water entering the first-stage water tank at 2.64 bar, do not set a cold section at the head, and open the first water tank in this section for cooling;

[0054] Control the pressure of the cooling water entering the second-stage water tank at 2.09 bar, the length of the head cooling section in this section is 19.5m, the length of the tail cooling section is 5.03m, and open the first water tank in this section for cooling;

[0055] Control the pressure of the cooling water entering the third-stage water tank at 0.51 bar, the length of the head cooling section in this section is 10.02m, the length of the tail cooling section is 0.2m, and open the first water tank in this section for cooling;

[0056] 4) Rolling, during which, control the finishing mill exit size at 37.3mm 2 , the top-bottom size * the side sizes are:

[0057] 7.12mm * 6.47mm; The opening of the rolling guide at the 32nd stand is controlled at 0.91mm;

[0058] 5) Reducing and sizing rolling, during which the roll gaps of the 31st to 34th stands are adjusted to: the roll gap of the 31st stand is adjusted to 1.31 mm, the roll gap of the 32nd stand is adjusted to 1.01 mm, the roll gap of the 33rd stand is adjusted to 1.41 mm, and the roll gap of the 34th stand is adjusted to 1.40 mm;

[0059] 6) Subsequently, the subsequent processes are carried out conventionally.

[0060] After inspection and statistics: According to the statistics of downstream customers' use: 23,851 tons of finished product specification φ5.5 mm cord steel produced in this embodiment, and the occurrence times of intermittent ears of cord steel are 0 times.

[0061] Example 3

[0062] A control method for intermittent ears during the rolling process of cord steel, the steps are as follows:

[0063] 1) Converter smelting, casting into slabs after RH vacuum treatment;

[0064] 2) Heating the cast slabs, during which: controlling the temperatures of the head, middle and tail sections of the cast slabs as follows:

[0065] The head is controlled at 1013 °C, the middle is controlled at 1029 °C, and the tail is controlled at 1069 °C;

[0066] 3) Three-stage water cooling of the cast slabs, during which:

[0067] Controlling the pressure of the cooling water entering the water tank in the first stage at 2.56 bar, without a cold section at the head, and opening the first water tank in this section for cooling;

[0068] Controlling the pressure of the cooling water entering the water tank in the second stage at 2.12 bar, the length of the head cooling section in this section is 19.8 m, the length of the tail cooling section is 5.01 m, and opening the first water tank in this section for cooling;

[0069] Controlling the pressure of the cooling water entering the water tank in the third stage at 0.61 bar, the length of the head cooling section in this section is 9.99 m, the length of the tail cooling section is 0.3 m, and opening the first water tank in this section for cooling;

[0070] 4) Rolling is carried out, during which, controlling the finish rolling exit size at 37.3 mm 2 , the top-bottom size * side sizes are at:

[0071] 7.08 mm * 6.49 mm; the opening of the rolling guide on the 32nd stand is controlled at 0.90 mm;

[0072] 5) Reducing and sizing rolling, during which the roll gaps of the 31st to 34th stands are adjusted to: the roll gap of the 31st stand is adjusted to 1.30 mm, the roll gap of the 32nd stand is adjusted to 0.99 mm, the roll gap of the 33rd stand is adjusted to 1.39 mm, and the roll gap of the 34th stand is adjusted to 1.39 mm;

[0073] 6) Subsequently, the subsequent processes are carried out conventionally.

[0074] After inspection and statistics: According to the statistics of downstream customers' use: The finished product specification of the wire rod steel produced in this embodiment is ф5.5 mm, with a quantity of 19,838 tons, and the occurrence times of intermittent ears of the wire rod steel are 0 times.

[0075] Example 4

[0076] A control method for intermittent ears during the rolling process of wire rod steel, the steps of which are as follows:

[0077] 1) Converter smelting, and casting into billets after RH vacuum treatment;

[0078] 2) Heating the billets, during which: control the temperatures of the head, middle, and tail sections of the billets as follows:

[0079] The head is controlled at 1012 °C, the middle is controlled at 1029 °C, and the tail is controlled at 1059 °C;

[0080] 3) Three-stage water cooling of the billets, during which:

[0081] Control the pressure of the cooling water entering the water tank in the first stage at 2.72 bar, do not set a cold section at the head, and open the first water tank in this section for cooling;

[0082] Control the pressure of the cooling water entering the water tank in the second stage at 2.29 bar, the length of the head cooling section in this section is 19.8 m, the length of the tail cooling section is 5.01 m, and open the first water tank in this section for cooling;

[0083] Control the pressure of the cooling water entering the water tank in the third stage at 0.55 bar, the length of the head cooling section in this section is 10.02 m, the length of the tail cooling section is 0.8 m, and open the first water tank in this section for cooling;

[0084] 4) Rolling is carried out, during which, control the finish rolling exit size at 37.45 mm 2 , the top-bottom size * the side sizes are at: 7.11 mm * 6.51 mm; the opening of the rolling guide in the 32nd stand is controlled at 0.90 mm;

[0085] 5) Reducing and sizing rolling, during which the roll gaps of the 31st to 34th stands are adjusted to: the roll gap of the 31st stand is adjusted to 1.29 mm, the roll gap of the 32nd stand is adjusted to 1.0 mm, the roll gap of the 33rd stand is adjusted to 1.4 mm, and the roll gap of the 34th stand is adjusted to 1.39 mm;

[0086] 6) Carry out subsequent processes routinely.

[0087] After inspection and statistics: According to the statistics of downstream customers' use: In this embodiment, 20,788 tons of finished product wire rod steel with a specification of ф5.5mm are produced, and the occurrence times of intermittent ears in the wire rod steel are 0 times.

[0088] Example 5

[0089] A control method for intermittent ears during the rolling process of wire rod steel, the steps thereof:

[0090] 1) Smelt in a converter, and cast into a billet after RH vacuum treatment;

[0091] 2) Heat the billet, during which: control the temperatures of the head, middle and tail sections of the billet as follows:

[0092] The head is controlled at 1001°C, the middle is controlled at 1032°C, and the tail is controlled at 1060°C;

[0093] 3) Carry out three-stage water cooling on the billet, during which:

[0094] Control the pressure of the cooling water entering the water tank in the first stage at 2.74 bar, do not set a cold section at the head, and open the first water tank in this section for cooling;

[0095] Control the pressure of the cooling water entering the water tank in the second stage at 2.13 bar, the length of the head cooling section in this section is 19.7 m, and the length of the tail cooling section is 5.01 m, and open the first water tank in this section for cooling;

[0096] Control the pressure of the cooling water entering the water tank in the third stage at 0.58 bar, the length of the head cooling section in this section is 10.01 m, and the length of the tail cooling section is 0.4 m, and open the first water tank in this section for cooling;

[0097] 4) Carry out rolling, during which, control the finish rolling exit size at 37.26 mm 2 , the top-bottom size * the side sizes are: 7.09 mm * 6.44 mm; the opening of the rolling guide on the 32nd stand is controlled at 0.89 mm;

[0098] 5) Carry out sizing rolling, during which adjust the roll gaps of the 31st to 34th stands to: adjust the roll gap of the 31st stand to 1.3 mm, the roll gap of the 32nd stand to 1.0 mm, the roll gap of the 33rd stand to 1.39 mm, and the roll gap of the 34th stand to 1.41 mm;

[0099] 6) Carry out subsequent processes routinely.

[0100] After inspection and statistics: According to the statistics of downstream customers' use: In this embodiment, 11,509 tons of finished product specification ф5.5mm cord steel are produced, and the occurrence frequency of intermittent ears in the cord steel is 0 times.

[0101] Example 6

[0102] A control method for intermittent ears during the rolling process of cord steel, the steps are as follows:

[0103] 1) Smelt in a converter, cast into a billet after RH vacuum treatment;

[0104] 2) Heat the billet, during which: control the temperatures of the head, middle and tail sections of the billet as follows:

[0105] The head is controlled at 1004°C, the middle is controlled at 1031°C, and the tail is controlled at 1061°C;

[0106] 3) Carry out three-stage water cooling on the billet, during which:

[0107] Control the pressure of the cooling water entering the water tank in the first stage at 2.71 bar, do not set a cold section at the head, and open the first water tank in this section for cooling;

[0108] Control the pressure of the cooling water entering the water tank in the second stage at 2.32 bar, the length of the head cooling section in this section is 19.8 m, the length of the tail cooling section is 5.01 m, and open the first water tank in this section for cooling;

[0109] Control the pressure of the cooling water entering the water tank in the third stage at 0.57 bar, the length of the head cooling section in this section is 10.01 m, the length of the tail cooling section is 0.3 m, and open the first water tank in this section for cooling;

[0110] 4) Carry out rolling, during which, control the finish rolling exit size at 37.15 mm 2 , the sky-earth size * the size on both sides is: 7.15 mm * 6.49 mm; the opening of the rolling guide on the 32nd stand is controlled at 0.89 mm;

[0111] 5) Carry out sizing rolling, during which adjust the roll gaps from the 31st to the 34th stands to: adjust the roll gap of the 31st stand to 1.29 mm, the roll gap of the 32nd stand to 0.99 mm, the roll gap of the 33rd stand to 1.39 mm, and the roll gap of the 34th stand to 1.39 mm;

[0112] 6) Carry out subsequent processes conventionally.

[0113] After inspection and statistics: According to the statistics of downstream customers' use: In this embodiment, 12,771 tons of finished product specification ф5.5mm cord steel are produced, and the occurrence frequency of intermittent ears in the cord steel is 0 times.

[0114] Example 7

[0115] A control method for intermittent ears during the rolling process of cord steel, comprising the following steps:

[0116] 1) Smelting in a converter, casting into billets after RH vacuum treatment;

[0117] 2) Heating the billets, during which: control the temperatures of the head, middle, and tail sections of the billets as follows:

[0118] The head is controlled at 1015 °C, the middle is controlled at 1023 °C, and the tail is controlled at 1057 °C;

[0119] 3) Conduct three-stage water cooling on the billets, during which:

[0120] Control the pressure of the cooling water entering the water tank in the first stage at 2.71 bar, do not set a cooling section at the head, and open the first water tank in this section for cooling;

[0121] Control the pressure of the cooling water entering the water tank in the second stage at 2.18 bar, the length of the head cooling section in this section is 19.8 m, the length of the tail cooling section is 4.99 m, and open the first water tank in this section for cooling;

[0122] Control the pressure of the cooling water entering the water tank in the third stage at 0.58 bar, the length of the head cooling section in this section is 10.01 m, the length of the tail cooling section is 0.8 m, and open the first water tank in this section for cooling;

[0123] 4) Conduct rolling, during which, control the finish rolling exit size at 37.26 mm 2 , the top-bottom size * side sizes are at: 7.19 mm * 6.49 mm; the opening of the rolling guide in the 32nd stand is controlled at 0.91 mm;

[0124] 5) Reducing and sizing rolling, during which adjust the roll gaps of the 31st to 34th stands to: adjust the roll gap of the 31st stand to 1.3 mm, the roll gap of the 32nd stand to 1.01 mm, the roll gap of the 33rd stand to 1.41 mm, and the roll gap of the 34th stand to 1.39 mm;

[0125] 6) Conduct subsequent processes conventionally.

[0126] After testing and statistics: According to the statistics of downstream customers: The finished product specification of the cord steel produced in this embodiment is ф5.5 mm, with a quantity of 10,922 tons, and the occurrence times of intermittent ears of the cord steel are 0 times.

[0127] This specific embodiment is only the best example and is not a restrictive implementation of the technical solution of the present invention.

Claims

1. A method for controlling intermittent ears during the rolling process of cord steel, comprising the following steps: 1) Converter smelting, RH vacuum treatment and then casting into billets; 2) The ingot is heated, during which the temperatures of the head, middle and tail of the ingot are controlled as follows: The head is controlled at 1000-1020℃, the middle is controlled at >1020 to 1040℃, and the tail is controlled at 1050-1070℃; 3) The rolled piece is subjected to three-stage water cooling, during which: Control the pressure of the first cooling water inlet tank at 2.5-2.8 bar, do not set a cooling section at the head, and open the first water tank in this section for cooling; Control the second section cooling water inlet tank pressure at 2.0-2.5 bar, the head cooling section length is 20±0.5m, The length of the tail cooling section is 5±0.5m, and the first water tank in this section is opened for cooling; Control the third section cooling water inlet tank pressure at 0.4-0.8 bar, the head cooling section length is 10±0.5m, The tail cooling section is 0 to 1 m long, and the first water tank in this section is opened for cooling; 4) Rolling is performed, during which the finishing outlet size is controlled to be 37.2-37.5 mm 2 , the size of the top and bottom * the size of the sides are: 7.05~7.15mm*6.45~6.65mm; the opening of the rolling guide of the 32nd rack is controlled at 0.9±0.02mm; 5) Perform sizing, during which the roll gaps of the 31st to 34th stands are adjusted to: the roll gap of the 31st stand is adjusted to 1.3±0.01mm, the roll gap of the 32nd stand is adjusted to 1.0±0.01mm, the roll gap of the 33rd stand is adjusted to 1.4±0.01mm, and the roll gap of the 34th stand is adjusted to 1.4±0.01mm; 6) Carry out subsequent processes as usual.

2. A method for controlling discontinuous ears during the rolling process of a cord steel as claimed in claim 1, characterized in that: The temperatures of the head, middle and tail of the ingot are as follows: the head is controlled at 1000-1015°C, the middle is controlled at 1025 to 1035°C, and the tail is controlled at 1055-1065°C.

3. The method for controlling discontinuous ears during the rolling process of cord steel according to claim 1, characterized in that: The above-mentioned top and bottom dimensions*side dimensions: the top and bottom dimensions refer to the gap between the finishing upper roller ring and the finishing lower roller ring; the side dimensions refer to the diameter dimensions between the two sides of the finishing roller ring.