Method for controlling the bending of bars during cooling after rolling

Abstract

The present invention relates to a method for controlling the bending of bars during cooling after rolling. The method effectively controls the cooling control process, the cooling bed step, the multiple-length shear advance coefficient and the cooling bed equipment according to the rolling specifications and the steel type, thereby solving the problem of the bending of bars during cooling after rolling. The bending phenomenon of the bars during cooling after rolling is greatly improved, thereby improving the processing efficiency and the yield rate of the subsequent process.

Description

Technical Field

[0001] The present invention relates to the technical field of steel metallurgy production and manufacturing, and in particular to a method for controlling the bending of a bar during cooling after rolling. Background Art

[0002] In the bar production process, the phenomenon of bending during cooling after rolling is very common, causing the head, middle and tail of the bar to bend, affecting the processing of the bar in subsequent steps and reducing production efficiency. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a method for controlling the bending of bars during cooling after rolling, which effectively solves the problem of bending of bars during cooling after rolling.

[0004] The technical solution adopted by the present invention is: a method for controlling the bending of a bar during cooling after rolling, characterized in that: according to the rolling specifications and steel grades, the cooling process, the cooling bed step, the multi-length shear advance coefficient and the cooling bed equipment are controlled, specifically comprising the following steps:

[0005] S1. Controlled cooling process: the temperature of the cooling bed on the rolled piece is ≤1000℃;

[0006] S2. Cooling bed step selection:

[0007] Rolling specifications Φ12-28, steel grade HRB400E, cooling bed step 60-70mm; rolling specifications Φ32-40, steel grade HRB400E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB500E, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB500E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB600E and above, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB600E and above, cooling bed step 125-135mm;

[0008] S3, setting of advance coefficient of multiple shear:

[0009] Rolling specification Φ12, leading coefficient 1.03 ~ 1.05; rolling specification Φ14, leading coefficient 1.04 ~ 1.06; rolling specification Φ16 ~ 20, leading coefficient 1.05 ~ 1.07; rolling specification Φ22, leading coefficient 1.06 ~ 1.08; rolling specification Φ25, leading coefficient 1.26 ~ 1.27; rolling specification Φ28, leading coefficient 1.265 ~ 1.275; rolling specification Φ32 ~ 40, leading coefficient 1.275 ~ 1.285;

[0010] S4. Precision control of cooling bed equipment: control the elevation deviation of the moving beam and the height deviation of the moving rack, the wear of the eccentric wheel and roller, and the wear of the rack end.

[0011] Preferably, in step S1, the cooling bed temperature of rolled pieces made of HRB400E material is ≤880°C, the cooling bed temperature of rolled pieces made of HRB500E material is ≤950°C, and the cooling bed temperature of rolled pieces made of HRB600E and above series is ≤1000°C.

[0012] Preferably, in step S4, the elevation of the movable beam is measured, and padding or reducing padding is adopted for movable beams that are not within the standard range to ensure that the elevation deviation of the movable beam and the height deviation of the movable rack are ≤3 mm.

[0013] Preferably, in step S4, the height deviation of the movable beam and the height deviation of the movable rack are ≤3 mm.

[0014] Preferably, the wear of the eccentric wheel and the roller is ≤2mm.

[0015] Preferably, in step S4, the wear on the rack end is ≤3 mm.

[0016] The beneficial effects achieved by the present invention are as follows: the present invention effectively controls the cooling control process, cooling bed step distance, multiple shear advance coefficient and cooling bed equipment according to the rolling specifications and steel types, solves the problem of bar bending after cooling and rolling, greatly improves the bending phenomenon of bar bending after cooling and improves the processing efficiency and yield rate of the subsequent process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the main structure of the walking cooling bed;

[0018] Figure 2 Height difference of the cooling bed moving beam base (positive value is high, negative value is low);

[0019] Among them: 1. Input roller; 2. Brake plate; 3. Straightening plate; 4. Stationary rack; 5. Moving rack; 6. Roller seat; 7. Roller; 8. Eccentric wheel; 9. Moving rack frame; 10. Rack seat. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] The present invention provides a method for controlling the bending of a bar during cooling after rolling, which controls the cooling process, cooling bed step, multi-length shear advance coefficient, and cooling bed equipment according to the rolling specifications and steel type, and specifically includes the following steps:

[0022] S1. Controlled cooling process: The upper cooling bed temperature of HRB400E rolled products is ≤880℃; the upper cooling bed temperature of HRB500E rolled products is ≤950℃; the upper cooling bed temperature of HRB600E and above rolled products is ≤1000℃;

[0023] Considering that as the strength of rolled pieces increases, the use of a lower upper cooling bed controlled cooling process will result in the rolled pieces' strength-to-yield ratio not meeting the standard. While the use of a higher upper cooling bed controlled cooling process can solve the problem of unsuitable strength-to-yield ratio caused by high-strength rebar, it is very easy to cause bending during the subsequent cooling process due to the excessively high temperature. Through process adjustment, the above controlled cooling process can solve the problem of unsuitable strength-to-yield ratio and inability to achieve bending at the same time.

[0024] S2. Cooling bed step selection:

[0025] Rolling specifications Φ12-28, steel grade HRB400E, cooling bed step 60-70mm; rolling specifications Φ32-40, steel grade HRB400E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB500E, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB500E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB600E and above, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB600E and above, cooling bed step 125-135mm;

[0026] The larger the rolled piece, the slower the heat dissipation. If the step size is too small, the heat dissipation will be slow and uneven, which can easily lead to bending. Similarly, the higher the strength of the rolled piece, the higher the upper cooling bed temperature. If the step size is too small, the heat dissipation will be slow and uneven, which can easily lead to bending.

[0027] S3, setting of advance coefficient of multiple shear:

[0028] Rolling specification Φ12, leading coefficient 1.03 ~ 1.05; rolling specification Φ14, leading coefficient 1.04 ~ 1.06; rolling specification Φ16 ~ 20, leading coefficient 1.05 ~ 1.07; rolling specification Φ22, leading coefficient 1.06 ~ 1.08; rolling specification Φ25, leading coefficient 1.26 ~ 1.27; rolling specification Φ28, leading coefficient 1.265 ~ 1.275; rolling specification Φ32 ~ 40, leading coefficient 1.275 ~ 1.285;

[0029] The smaller the size of the rolled piece, the faster the rolling speed. At the same time, the smaller the shear force required for the rolled piece, the smaller the shear speed drop during the shearing process. Therefore, setting a smaller advance coefficient can ensure that the shear speed after shearing is greater than the speed of the rolled piece, thereby preventing elbows at the end after shearing. Similarly, the larger the size of the rolled piece, the slower the rolling speed. At the same time, the greater the shear force required for shearing, the greater the shear speed drop during the shearing process. Therefore, a larger advance coefficient is required to ensure that the shear speed after shearing is greater than the speed of the rolled piece.

[0030] S4. Precision control of cooling bed equipment: Control the deviation of the movable beam elevation and the movable rack height, the wear of the eccentric wheel and roller, and the wear of the rack end; the deviation of the movable beam elevation and the movable rack height is ≤3mm, the wear of the eccentric wheel and roller is ≤2mm, and the wear of the rack end is ≤3mm; measure the elevation of the movable beam, and take measures such as adding or removing pads for movable beams that are not within the standard range to ensure that the deviation of the movable beam elevation and the movable rack height is ≤3mm;

[0031] After rolling, the rolled piece is placed on the cooling bed. The precision control of the cooling bed equipment does not meet the requirements, causing bending when placing it on the cooling bed. The deviation between the movable beam elevation and the movable rack height exceeds the standard. In some places, the rack cannot transport the steel backward, resulting in inconsistent steel support and failure to synchronously install the straightening plate, causing bending. The eccentric wheel and supporting roller are worn beyond the standard, causing the rack frame height to be too low. In some cases, the rack cannot support the rolled piece and synchronously transports it forward, causing the rolled piece to bend.

[0032] like Figure 1 As shown, it is a conventional step-type cooling bed, including an input roller 1, a brake plate 2, a straightening plate 3, a movable rack 5, a static rack 4, an eccentric wheel 8 and a roller 7. The cooling bed is generally driven synchronously by four volute reducers to ensure that the cooling bed can continuously perform the four actions of rising, moving forward, falling and retreating.

[0033] The elevation of the cooling bed moving beam base is measured during regular maintenance and long-term shutdown. The data are as follows:

[0034] Measured from north to south, the mean of all measuring points is zero, values ​​above the mean are positive, and values ​​below the mean are negative. Unit: mm:

[0035]

[0036]

[0037] By measuring the elevation of the moving beam, measures such as adding or reducing pads are taken for moving beams that are not within the standard range: for example, if the elevation of moving beam No. 8 is higher than 4mm, a 1mm pad is subtracted to ensure that its height deviation is ≤3mm.

[0038] On-site results:

[0039] From May 1 to May 30, 2024, the rolling specifications include Φ12, Φ14, Φ16, Φ18, Φ25, etc., and the products include HRB400E and HRB500E.

[0040] Effect 1: From May 5 to 12, 2024, Φ14 specification, steel grade HRB400E was produced. The temperature of the cooling bed on the rolled piece was controlled at 860℃±5℃, the cooling bed step was 60mm, the multiple shear advance coefficient was 1.03, and steel was bent during the cooling bed production process; when the cooling bed step was adjusted to 63mm and the multiple shear advance coefficient was adjusted to 1.04, the phenomenon of steel bending on the cooling bed was significantly improved.

[0041] Effect 2: From May 23 to 27, 2024, Φ20 steel was produced using HRB500E steel grade. The upper cooling bed temperature was controlled at 920°C ± 5°C, the cooling bed pitch was 68mm, and the shear advance coefficient was 1.07. Bent steel rarely occurred during production. In the production of Φ22 steel, a 68mm pitch and a shear advance coefficient of 1.07 were used. Previously, after two hours of continuous rolling, bent steel would appear near the 50-meter and 90-meter positions of the cooling bed. During downtime, 2mm pads were added to the moving beam base at these locations. No bent steel was observed during subsequent production.

[0042] Effect 3: On May 3-4 and 13-14, 2024, Φ25 steel was rolled using HRB400E. The cooling bed temperature was controlled at 870°C ± 5°C, with a 130mm pitch and a shear advance coefficient of 1.265. Bend occurred during the cooling bed production process. When the pitch was adjusted to 133 and the shear advance coefficient to 1.268, the bend at the end of the rolled piece was reduced, and the bending on the cooling bed was reduced.

[0043] It should be noted that the description of the above technical solutions is illustrative only. This specification may be embodied in various forms and should not be construed as limiting the technical solutions set forth herein. Rather, these descriptions are provided to ensure that the disclosure of the present invention is thorough and complete and to fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of the present invention are limited only by the scope of the claims.

[0044] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and is susceptible to numerous variations. Any simple modifications, equivalent variations, and modifications to the above embodiments based on the technical essence of the present invention shall be deemed to fall within the scope of protection of the present invention.

Claims

1. A method for controlling the bending of a bar during cooling after rolling, characterized in that: According to the rolling specifications and steel grades, the controlled cooling process, cooling bed step, multi-length shear advance coefficient and cooling bed equipment are controlled, which specifically includes the following steps: S1. Controlled cooling process: the temperature of the cooling bed on the rolled piece is ≤1000℃; S2. Cooling bed step selection: Rolling specifications Φ12-28, steel grade HRB400E, cooling bed step 60-70mm; rolling specifications Φ32-40, steel grade HRB400E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB500E, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB500E, cooling bed step 125-135mm; rolling specifications Φ12-22, steel grade HRB600E and above, cooling bed step 60-70mm; rolling specifications Φ25-40, steel grade HRB600E and above, cooling bed step 125-135mm; S3, setting of advance coefficient of multiple shear: Rolling specification Φ12, leading coefficient 1.03 ~ 1.05; rolling specification Φ14, leading coefficient 1.04 ~ 1.06; rolling specification Φ16 ~ 20, leading coefficient 1.05 ~ 1.07; rolling specification Φ22, leading coefficient 1.06 ~ 1.08; rolling specification Φ25, leading coefficient 1.26 ~ 1.27; rolling specification Φ28, leading coefficient 1.265 ~ 1.275; rolling specification Φ32 ~ 40, leading coefficient 1.275 ~ 1.285; S4. Precision control of cooling bed equipment: control the elevation deviation of the moving beam and the height deviation of the moving rack, the wear of the eccentric wheel and roller, and the wear of the rack end.

2. The method for controlling the bending of a bar during cooling after rolling according to claim 1, characterized in that: In step S1, the upper cooling bed temperature of the rolled piece made of HRB400E material is ≤880°C, the upper cooling bed temperature of the rolled piece made of HRB500E material is ≤950°C, and the upper cooling bed temperature of the rolled piece made of HRB600E and above series is ≤1000°C.

3. The method for controlling the bending of a bar during cooling after rolling according to claim 1, characterized in that: In step S4, the elevation of the movable beam is measured, and measures such as adding or removing pads are taken for movable beams that are not within the standard range to ensure that the elevation deviation of the movable beam and the height deviation of the movable rack are ≤3mm.

4. The method for controlling the bending of a bar during cooling after rolling according to claim 1, characterized in that: In step S4, the height deviation of the movable beam and the height deviation of the movable rack are ≤3 mm.

5. The method for controlling the bending of a bar during cooling after rolling according to claim 4, characterized in that: The wear of eccentric wheel and roller is ≤2mm.

6. The method for controlling the bending of a bar during cooling after rolling according to claim 1, characterized in that: In step S4, the rack end wear is ≤3 mm.

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