A stable production method of non-oriented high-grade silicon steel hot continuous rolling

Abstract

This invention discloses a stable hot continuous rolling production method for non-oriented high-grade silicon steel, with the following parameter control: PC steel and W1300 are used as transition materials before rolling; the furnace time and furnace top temperature are controlled; the intermediate billet thickness is controlled at 37-38 mm; the head lateral bend is controlled at ±20 mm, and the tail lateral bend at ±30 mm; the transition material is used for gradient thickness adjustment; the finishing mill inlet temperature is controlled to be no lower than 940℃, and the final rolling temperature is 860±10℃; the crown is 30±5 μm; in case of abnormal shutdown for more than 30 minutes, 2-3 pieces are recycled from each furnace; before production, the wear, opening degree, and alignment of the coiling side guide plate are inspected, and the plate is replaced if the wear exceeds 5 mm, and recalibrated if the opening degree or alignment exceeds the standard; if tail fragments appear during coiling, they must be cleaned up before notifying the finishing mill process to continue feeding steel. This invention achieves continuous, stable, and high-precision rolling of high-grade silicon steel through the solidification and coordinated control of parameters throughout the entire process of heating furnace, roughing, finishing, and coiling.

Description

Technical Field

[0001] This invention belongs to the field of metal pressure processing technology, specifically relating to a stable hot continuous rolling production method for non-oriented high-grade silicon steel. Background Technology

[0002] Non-oriented high-grade silicon steel is a core material for the cores of high-end equipment such as drive motors for new energy vehicles, high-efficiency motors, and wind power converters. It is required to have characteristics such as low iron loss, high magnetic induction, high dimensional accuracy, and excellent plate shape. Hot rolling is a key process in the production of silicon steel, which directly determines the plate shape, crown, plate uniformity, microstructure uniformity, and final magnetic properties.

[0003] As silicon steel develops towards high silicon content, ultra-thinness, and wide widths, the production difficulty has increased dramatically. Existing conventional hot rolling processes have revealed many prominent problems in the mass production of high-grade silicon steel (W350 and above, WV2000 and above new energy silicon steel): Insufficient heating and slab control: unreasonable heating schedule, poor matching of transition materials, insufficient slab time in the furnace, and uneven temperature can easily lead to fluctuations in rolling load and deterioration of slab shape; lack of direct loading temperature control and non-standard holding time further aggravate temperature instability.

[0004] Weak control of intermediate billets in roughing: The thickness of intermediate billets fluctuates greatly and the lateral bending exceeds the standard. After the automatic control of the sickle-shaped bend is cancelled, the plate shape is difficult to stabilize, which can easily lead to problems such as sudden wedge-shaped changes, deviation, and strip breakage in finishing rolling.

[0005] Uncontrolled transition and thickness modification in finishing rolling: There is no unified standard for the transition thickness after the start of rolling and roll change, and arbitrary and batch thickness modification occurs frequently, resulting in large dimensional fluctuations and low yield; the opening, centering and compensation values ​​of the side guide plate lack graded settings, resulting in poor strip centering and serious head and tail deviation.

[0006] Lack of coordinated control of temperature and crown: There are no strict red lines for the entry temperature and final rolling temperature of the finishing mill; unreasonable use of cooling water leads to large temperature drop at the edge and crown fluctuation; non-standard use of the roll system exacerbates the loss of control over the shape and dimensional accuracy of the plate.

[0007] Abnormal operating conditions lack standardized handling: There is no unified process for shutdown, roll change and return to the furnace strategy, transition rhythm and temperature recovery, which can easily lead to problems such as insufficient temperature, uncontrolled thickness modification, increased scrap steel and decreased operating rate.

[0008] Insufficient linkage between coiling and finishing rolling: wear of side guide plates, lack of inspection standards for opening and centering, and untimely removal of tail debris can easily lead to defects such as steel piling, scratches, and poor coil shape.

[0009] Currently, the industry mostly adopts segmented control and experience-based operation, lacking a stable, integrated production method covering the entire process from heating to roughing, finishing, and coiling. This makes it difficult to meet the continuous, stable, and high-precision rolling requirements of high-grade silicon steel. Therefore, developing a stable production method for hot continuous rolling of high-grade silicon steel with solidified parameters throughout the entire process and rapid recovery from anomalies is of significant practical importance for improving product quality and production efficiency. Summary of the Invention

[0010] Technical problem solved: To address the above-mentioned technical problems, this invention provides a stable hot continuous rolling production method for non-oriented high-grade silicon steel. By solidifying and coordinating the parameters of the entire process, including heating furnace, roughing, finishing, and coiling, continuous, stable, and high-precision rolling of high-grade silicon steel can be achieved.

[0011] Technical solution: A stable hot continuous rolling production method for non-oriented high-grade silicon steel, including the following parameter control: (1) Control of heating furnace process: PC steel and non-oriented silicon steel W1300 are used as transition materials before rolling; control the furnace time: W350, WV2000, WV1900 not less than 190 min; W310 and higher grade silicon steel, WV1500 and higher grade new energy silicon steel not less than 200 min, where WV represents new energy silicon steel, which is mainly used for new energy vehicle drive motors; control the furnace top temperature: preheating section 980±20℃, first heating section 1080±20℃, second heating section 1110±20℃, soaking section 1110±20℃; (2) Rough rolling process control: The thickness of the intermediate billet is controlled at 37~38mm; the automatic adjustment of the sickle bend is cancelled, and the side bend of the head is controlled within ±20mm and the side bend of the tail is controlled within ±30mm; (3) Finishing process control: SPHC and ordinary W1300 are used for gradient transition before rolling high grade silicon steel, and batch thickening is prohibited; the entry temperature of finishing mill is controlled not lower than 940 ℃, and the final rolling temperature is controlled at 860±10℃; the crown target is controlled at 30±5μm, of which the crown target of the first three blocks is increased to 35μm; the cooling water is turned off for secondary descaling, side spray and top spray, and F2~F4 rolling lubrication is put into use; the number of times F1 and F2 are used is controlled not to exceed 3 times, and new grinding rolls are used for F3 and F4. (4) Abnormal working conditions and rhythm control: When the abnormal shutdown is 30~60min, 2 pieces are recycled for each heating furnace; when the shutdown is more than 60min, 3 pieces are recycled for each heating furnace; when the transition material is replaced with high grade silicon steel, manually compensate the F2~F7 looper tension by 5%~10%, and cancel it after production stabilizes. (5) Inspection of coiling equipment and linkage control of finishing rolling: Before production, the wear, opening degree and centering of the side guide plate of the coiling process are inspected. When the wear exceeds 5mm, it is replaced. When the opening degree deviation exceeds 10mm or the centering deviation exceeds 5mm or the centering is recalibrated, the coiling process is notified to continue feeding steel. When tail fragments appear during coiling, they must be cleaned up and the finishing rolling process is notified before steel can continue to be fed.

[0012] Preferably, in the heating furnace process, the temperature of the slab directly loaded is controlled to be no less than 450°C, and rolling is completed within 6 hours after storage in the heat preservation pit.

[0013] Preferably, in the heating furnace process, the surface, burrs and edge quality of the slab are checked before it is loaded into the furnace, and it is loaded into the furnace only if there are no abnormalities.

[0014] Preferably, in the roughing process, if the thickness deviation of the intermediate billet exceeds 1 mm, the roll change time is used to recalibrate.

[0015] Preferably, in the roughing process, when continuous production does not meet the side bending requirements, the R2 roll gap calibration is completed using the roll changing window.

[0016] Preferably, in the finishing rolling process, the target thickness of the first three transition materials W1300 in normal rolling is controlled to be 2.7mm, 2.5mm and 2.5mm respectively. The target thickness of the first three high-grade silicon steel is changed to 2.4mm, and subsequent production is controlled according to the target thickness of 2.3mm.

[0017] Preferably, during the finishing rolling process, when changing rolls or stopping the machine for more than 30 minutes, the thickness target of the first three high-grade silicon steel rolls is gradually increased to 3.5mm, 2.7mm and 2.4mm respectively.

[0018] Preferably, in the finishing rolling process, after changing the rolls, the opening degree and centering of the F2~F7 side guide plates are checked. If the opening degree deviation exceeds 10mm or the centering deviation exceeds 5mm, the plates are recalibrated.

[0019] Preferably, in the finishing rolling process, dynamic compensation is performed on the alignment of the F2~F7 side guide plates. The graded compensation values ​​of the F2~F7 side guide plates in the threading section and the middle section are as follows: target finished width of high grade silicon steel +30mm, +30mm, +40mm, +50mm, +60mm, +70mm, and the graded compensation values ​​at the tail are as follows: +30mm, +30mm, +40mm, +50mm, +80mm, +120mm.

[0020] Preferably, during the winding process, the pressure of the side guide plate is controlled to ensure that the coil shape has no large misalignment and that there are no sparks after the steel is bitten.

[0021] Beneficial effects: This invention, through standardized, parameterized, and coordinated control of the entire process, can significantly reduce the thickness modification rate, strip breakage rate, and scrap rate, while improving the plate shape, dimensional accuracy, and yield, thus meeting the demand for large-scale and stable production of high-grade silicon steel for new energy applications. Attached Figure Description

[0022] Figure 1 This is a complete process flow diagram of the stable hot continuous rolling production method for non-oriented high-grade silicon steel according to the present invention. Figure 2 This is a schematic diagram of the rules for remelting under abnormal operating conditions and the thickness gradient of transition rolling. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, a stable hot continuous rolling production method for non-oriented high-grade silicon steel includes the following parameter control: 1. Precise control of the heating furnace process Before rolling, a combination of PC steel and W1300 transition material is used to ensure width matching and a stable temperature transition. Surface, burr, and edge quality checks are performed on the slabs before loading; unqualified slabs are prohibited from entering the furnace. The direct loading temperature of the slabs is no less than 450℃, and rolling is completed within 6 hours after storage in the heat preservation pit to avoid temperature loss. Strict control of furnace time is maintained: no less than 190 minutes for W350, WV2000, and WV1900; no less than 200 minutes for high-grade W310 and above, and new energy silicon steel of WV1500 and above, to ensure austenite homogenization and temperature uniformity. Temperature control within each section of the heating furnace is implemented within a fixed range; exceeding the process upper limit is strictly prohibited to prevent overheating, burning, and uneven temperature. A stable production rhythm is maintained to avoid billet temperature fluctuations caused by prolonged waiting time. The first two billets are closely monitored before tapping to prevent billet bending from affecting rolling.

[0025] 2. Stability control of intermediate billet thickness and shape during rough rolling The thickness of the intermediate billet is uniformly controlled within 37~38mm. If the thickness deviation exceeds 1mm, recalibration is immediately performed during roll change time. Automatic adjustment of the sickle bend is disabled to ensure the straightness of the intermediate billet. The lateral bend at the head is controlled within ±20mm, and the lateral bend at the tail is controlled within ±30mm to avoid abrupt changes in the wedge shape and deviation during finishing rolling. If the lateral bend requirements are not met during continuous production, the R2 roll gap calibration is promptly performed during roll change window to ensure the stability of the plate shape.

[0026] 3. Coordinated control of finishing rolling transition, temperature, crown, and equipment. For the first three transition plates during normal rolling, the thickness should be 2.7mm, 2.5mm, and 2.5mm respectively. The first high-grade silicon steel plate should be thickened to 2.4mm, and no more than three plates should be used; batch thickening is strictly prohibited. After changing rolls or prolonged shutdowns, the thickness should be gradually increased from 3.5mm to 2.7mm to 2.4mm to ensure stable load. The finishing mill inlet temperature should not be lower than 940℃, and the final rolling temperature should be controlled at 860±10℃. The crown target is 30±5μm, which should be increased to 35μm for the first three plates to ensure the shape and dimensional accuracy. After changing rolls, the opening degree and alignment of the F2~F7 side guide plates must be checked. If they exceed the standard, they must be recalibrated immediately. Cooling water should be optimized according to requirements, secondary descaling, side spraying, and top spraying should be turned off, and rolling lubrication of F2~F4 should be used to reduce edge temperature drop and shape fluctuation. The use of the roll system should be standardized: the F1 and F2 work rolls should not be used more than 3 times, and new grinding rolls should be used for F3 and F4 to improve the shape control capability. The dynamic compensation parameters for the side guide plates of the finishing mill F2~F7 are shown in Table 1 below: Table 1 Dynamic Compensation Parameters for Side Guide Plates of Finishing Mill F2~F7

[0027] Table 1 shows the graded compensation values ​​for the strip threading section, the middle section, and the tail section, achieving stable control of the strip's centering along its entire length.

[0028] 4. Abnormal operating conditions, remelting, and rhythm control like Figure 2 As shown, for each heating furnace with an abnormal shutdown of more than 30 minutes, 2 pieces should be returned to the furnace; for more than 60 minutes, 3 pieces should be returned. After returning to the furnace, the inlet temperature of the finishing mill must reach above 940℃ before steel can be fed in. When changing specifications, manually compensate the F2~F7 looper tension by 5%~10%, and cancel it after stabilization. Do not actively reduce the tension; slow down the pace for the first two pieces during the transition phase, and do not wait for the steel.

[0029] 5. Coiling equipment inspection and finishing rolling linkage control Before production, the wear, opening degree, and alignment of the coiling side guide plate are inspected. If the wear exceeds 5mm, it is replaced; if the opening or alignment exceeds the standard, it is recalibrated. The pressure of the side guide plate should be such that it does not produce large misalignment or sparks. If tail fragments appear during coiling, they must be cleaned up and the finishing mill must be notified before steel can continue to be fed, so as to achieve stable production through the linkage of finishing mill and coiling.

[0030] The technical solution of the present invention will be further described in detail below with reference to specific production grades and specifications.

[0031] Example 1: Production of WV2000 (1250mm / 2.3mm) high-grade silicon steel 1. Before the start of rolling in the heating furnace, arrange 6 PC steel slabs + 6 W1300 transition steel slabs, with the width difference controlled within 40mm. Before loading the slabs, check the surface, burrs, and edge quality; only load them into the furnace if no abnormalities are found. The direct loading temperature of the slabs is 480℃, and rolling is completed within 4 hours after storage in the insulation pit. The furnace time is controlled at 205 minutes. Furnace top temperatures: preheating section 980℃, first heating section 1080℃, second heating section 1110℃, soaking section 1110℃; furnace side temperatures are implemented according to the corresponding standards, and the upper limit is not exceeded throughout the process. The production rhythm is stable, with no long waiting times for steel. The first two slabs after tapping are closely monitored, and there are no abnormal bending of the slabs.

[0032] 2. The thickness of the intermediate billet in the roughing mill is set to 37.5mm, with a measured deviation of 0.6mm, which meets the requirement of ≤1mm; the automatic adjustment of the sickle bend is cancelled, and the side bend of the head of the intermediate billet is 15mm and the side bend of the tail is 22mm, which meets the control standard; there is no need to recalibrate the R2 roll gap.

[0033] 3. The thicknesses of the first three transition materials in the finishing mill were controlled to be 2.7mm, 2.5mm, and 2.5mm respectively; the first high-grade silicon steel was thickened to 2.4mm, with a total of 2 pieces used, not exceeding the limit of 3 pieces. The finishing mill inlet temperature was 952℃, meeting the requirement of ≥940℃; the final rolling temperature was 861℃, within the range of 860±10℃; the target crown was 30μm, with the first three pieces controlled at 35μm, and the actual crown was 33~36μm, with a fluctuation of ≤3μm. After changing the rolls, the opening and alignment of the side guide plates of F2~F7 were checked, and the deviations were all within the acceptable range; secondary descaling was turned off, and the finishing mill side spray and top spray were turned off. The rolling lubrication of F2~F4 was put into normal use, and the anti-stripping water was turned off. The finishing mill work rolls F1 and F2 were used twice, and F3 and F4 were new grinding rolls, meeting the requirements for roll system use.

[0034] 4. Before production, the coiling side guide plate was inspected. The wear was 3mm, the opening deviation was 6mm, and the centering deviation was 3mm, all of which were qualified. The pressure of the side guide plate was moderate, the coil shape had no large misalignment, and there were no sparks after the steel was bitten. A small amount of debris appeared during the coiling process. It was cleaned up in time, and the finishing mill was notified to resume steel feeding, so as to achieve stable production.

[0035] 5. The implementation results showed no thickness changes, no strip breaks, and no tailing throughout the process; the plate shape was straight, and the convexity was stable within 30±5μm; the dimensional accuracy was qualified, the yield rate increased by 4.3% compared to before, and the production smoothness was significantly improved.

[0036] Example 2: Production of W310 (1011mm / 2.3mm) high-grade silicon steel 1. The heating furnace is planned to use high-grade silicon steel before and after the heating furnace is controlled. The number of PC steel pieces is reduced to 4, and the number of W1300 transition material pieces remains at 6. After the slabs pass inspection, they are put into the furnace and the direct loading temperature is 465℃. The furnace time is 210 minutes, which meets the requirement of ≥200 minutes. The temperature is executed according to the standard and there is no overheating.

[0037] 2. The thickness of the intermediate billet during rough rolling is controlled at 38.0 mm with a deviation of 0.5 mm; the lateral bend at the head is 12 mm and the lateral bend at the tail is 25 mm, which meets the control requirements.

[0038] 3. Finishing Roll Control: Before this production run, a finishing roll change was performed. Production resumed with a gradient transition of 3.5mm → 2.7mm → 2.4mm. The finishing roll inlet temperature was 946℃, and the final rolling temperature was 858℃. The crown was 35μm for the first three sections and 30μm for the subsequent sections, and was kept stable. Side guides, cooling water, and the roll system all followed the standards. When changing specifications, the looper tension was manually compensated by 8%, which was removed after production stabilized. The base tension was not reduced.

[0039] 4. In case of a 40-minute shutdown during production, two pieces should be recycled from each furnace as required. After recycling, the entry temperature of the finishing mill should be raised to 945℃, and rolling should be resumed.

[0040] 5. Implementation results show that the entire production process was stable, with no batch thickness modifications or tape breakage / tailing issues; the plate shape, dimensions, and convexity all met the standards, and the magnetic properties were uniform.

Claims

1. A stable hot continuous rolling production method for non-oriented high-grade silicon steel, characterized in that, The following parameters are controlled: (1) Control of heating furnace process: PC steel and non-oriented silicon steel W1300 are used as transition materials before rolling; control the furnace time: W350, WV2000, WV1900 not less than 190 min; W310 and higher grade silicon steel, WV1500 and higher grade new energy silicon steel not less than 200 min, where WV represents new energy silicon steel, which is mainly used for new energy vehicle drive motors; control the furnace top temperature: preheating section 980±20℃, first heating section 1080±20℃, second heating section 1110±20℃, soaking section 1110±20℃; (2) Rough rolling process control: The thickness of the intermediate billet is controlled at 37~38mm; the automatic adjustment of the sickle bend is cancelled, and the side bend of the head is controlled within ±20mm and the side bend of the tail is controlled within ±30mm; (3) Finishing process control: SPHC and ordinary W1300 are used for gradient transition before rolling high grade silicon steel, and batch thickening is prohibited; the entry temperature of finishing mill is controlled not lower than 940 ℃, and the final rolling temperature is controlled at 860±10℃; the crown target is controlled at 30±5μm, of which the crown target of the first three blocks is increased to 35μm; the cooling water is turned off for secondary descaling, side spray and top spray, and F2~F4 rolling lubrication is put into use; the number of times F1 and F2 are used is controlled not to exceed 3 times, and new grinding rolls are used for F3 and F4. (4) Abnormal working conditions and rhythm control: When the abnormal shutdown is 30~60min, 2 pieces are recycled for each heating furnace; when the shutdown is more than 60min, 3 pieces are recycled for each heating furnace; when the transition material is replaced with high grade silicon steel, manually compensate the F2~F7 looper tension by 5%~10%, and cancel it after production stabilizes. (5) Inspection of coiling equipment and linkage control of finishing rolling: Before production, the wear, opening degree and centering of the side guide plate of the coiling process are inspected. When the wear exceeds 5mm, it is replaced. When the opening degree deviation exceeds 10mm or the centering deviation exceeds 5mm or the centering is recalibrated, the coiling process is notified to continue feeding steel. When tail fragments appear during coiling, they must be cleaned up and the finishing rolling process is notified before steel can continue to be fed.

2. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, During the heating furnace process, the temperature of the slab during direct loading is controlled to be no less than 450℃, and rolling is completed within 6 hours after storage in the heat preservation pit.

3. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, In the heating furnace process, the surface, burrs and edge quality of the slab are checked before it is loaded into the furnace. If there are no abnormalities, it is loaded into the furnace.

4. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, In the roughing process, if the thickness deviation of the intermediate billet exceeds 1 mm, the roll change time is used to recalibrate.

5. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, In the roughing process, when continuous production does not meet the side bending requirements, the R2 roll gap calibration is completed using the roll changing window.

6. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, In the finishing rolling process, the target thickness of the first three transition materials W1300 during normal rolling is controlled at 2.7mm, 2.5mm and 2.5mm respectively. The target thickness of the first three high-grade silicon steel rolling materials is changed to 2.4mm, and subsequent production is controlled according to the target thickness of 2.3mm.

7. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, During the finishing rolling process, when changing rolls or stopping the machine for more than 30 minutes, the thickness target of the first three high-grade silicon steel rolls should be gradually increased to 3.5mm, 2.7mm and 2.4mm respectively.

8. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, In the finishing rolling process, after changing the rolls, the opening degree and centering of the F2~F7 side guide plates are checked. If the opening degree deviation exceeds 10mm or the centering deviation exceeds 5mm, the plates are recalibrated.

9. The method for stable hot continuous rolling production of non-oriented high-grade silicon steel according to claim 1, characterized in that, During the finishing rolling process, dynamic compensation is applied to the alignment of the F2~F7 side guide plates. The graded compensation values ​​for the F2~F7 side guide plates in the threading section and the middle section are as follows: target finished width of high-grade silicon steel +30mm, +30mm, +40mm, +50mm, +60mm, +70mm. The graded compensation values ​​at the tail are as follows: +30mm, +30mm, +40mm, +50mm, +80mm, +120mm.

10. A stable hot continuous rolling production method for non-oriented high-grade silicon steel according to claim 1, characterized in that, During the winding process, the pressure of the side guide plate is controlled to ensure that the coil shape has no large misalignment and that there are no sparks after the steel is bitten.

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