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CN-121972512-A - Rolling method for improving steel plate shape of thin girder

CN121972512ACN 121972512 ACN121972512 ACN 121972512ACN-121972512-A

Abstract

The invention discloses a rolling method for improving the shape of a thin girder steel plate, and belongs to the technical field of metal material rolling. The method is characterized in that a process of combining rough rolling two frames (R1, R2) '3+3 pass' reversible rolling and finish rolling seven frames (F1-F7) continuous rolling is adopted, and the rolling reduction of rough rolling and finish rolling is subjected to full-flow linkage optimization distribution. The invention can inhibit the plate shape defect from the source, obviously improve the plate shape quality of the thin girder steel with the thickness of 2.0-4.0 mm, ensure that the flatness error is less than or equal to 3mm/m, the thickness tolerance is less than or equal to +/-0.05 mm, and has strong process suitability, thereby being easy to popularize and apply on the existing hot rolling production line.

Inventors

  • LI PENG
  • SU CHENG
  • ZHANG ZHIGANG
  • KANG XU

Assignees

  • 内蒙古包钢钢联股份有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. A rolling method for improving the shape of a thin girder steel plate is characterized by comprising the following procedures of blank preparation, heating, rough rolling, finish rolling, laminar cooling and coiling; The rough rolling process adopts two frames R1 and R2 to carry out reversible rolling of 3+3 times, the total reduction rate is controlled to be 70% -85%, wherein the reduction rate of 3 times of the frame R1 is reduced by each time, and the reduction rate of 3 times of the frame R2 is reduced by each time; The finish rolling process comprises the steps of performing continuous rolling by adopting seven frames F1-F7, controlling the total rolling reduction to be 80% -95%, rolling to obtain thin girder steel with the thickness of 2.0-4.0 mm, wherein the frames F1-F3 adopt a large rolling strategy with single-pass rolling reduction of 25% -35%, the frames F4-F7 adopt a small rolling strategy with single-pass rolling reduction of 8% -15%, and performing plate shape control by matching with a working roll bending technology; the rough rolling process provides an intermediate billet with uniform thickness and uniform temperature for the finish rolling process.
  2. 2. The rolling method according to claim 1, wherein the specific parameters of the rough rolling process are: The reduction of the first pass of the R1 frame is 30-40 mm, the reduction of the second pass is 25-35 mm, and the reduction of the third pass is 20-25 mm; The reduction of the first pass of the R2 frame is 15-20 mm, the reduction of the second pass is 10-15 mm, and the reduction of the third pass is 5-10 mm; the thickness of the intermediate billet obtained after rough rolling is 45-60 mm.
  3. 3. The rolling method according to claim 1 or 2, wherein in the rough rolling process, the rolling speed is controlled to be 1.5-3.0 m/s, high-pressure water with the pressure of more than or equal to 18MPa is adopted for descaling, and the rolls of the R1 and R2 frames are wear-resistant alloy rolls, and the roll surface roughness is controlled to be 0.8-1.6 μm.
  4. 4. The rolling method according to claim 1, wherein in the finish rolling step, the cumulative rolling reduction of the F1 to F3 stands is 60% to 70%, and the cumulative rolling reduction of the F4 to F7 stands is 15% to 25%.
  5. 5. The rolling method according to claim 1, wherein in the finish rolling process, a closed loop strip shape control system is used for monitoring and adjusting the strip shape in real time, and the roll bending force of the work roll bending technology is 500-1500 kN.
  6. 6. The rolling method according to claim 1, wherein the inlet temperature of the finish rolling process is controlled to 1000-1050 ℃, the outlet temperature is controlled to 850-900 ℃, and the rolling speed is controlled to 5-12 m/s.
  7. 7. The rolling method according to claim 1, wherein the laminar cooling step adopts a sectional cooling mode, the cooling speed is 15-30 ℃ per second, the final cooling temperature is controlled to be 600-650 ℃, the coiling temperature in the coiling step is controlled to be 580-620 ℃, and the coiling tension is controlled to be 10-20 kn.
  8. 8. The rolling method according to claim 1, wherein the width of the thin girder steel is 1000-180mm, the flatness error of the finished plate shape is less than or equal to 3mm/m, and the thickness tolerance is less than or equal to + -0.05 mm.
  9. 9. The rolling method according to claim 1, wherein in the blank preparation process, a continuous casting slab with a thickness of 150-200 mm is adopted, and the chemical components of the continuous casting slab are, by weight, 0.06% -0.08% of C, 0.10% -0.15% of Si, 1.20% -1.60% of Mn, less than or equal to 0.018% of P, less than or equal to 0.015% of S, and the balance of Fe and unavoidable impurities.
  10. 10. The rolling method according to claim 1, wherein in the heating step, the slab is heated to 1180-1250 ℃ in a step-by-step heating furnace for 30-60 min, and the temperature difference between the upper surface and the lower surface of the slab is controlled to be less than or equal to 30 ℃.

Description

Rolling method for improving steel plate shape of thin girder Technical Field The invention relates to the technical field of metal material rolling, in particular to a rolling method for improving the shape of a thin girder steel plate, which is particularly suitable for hot rolling production of automobile girder steel with the thickness of 2.0-4.0 mm. Background The automobile girder steel is a key structural material for manufacturing an automobile frame, and the plate shape quality (such as flatness and thickness uniformity) directly influences the assembly precision and welding quality of the frame, and the bearing safety and light weight level of the whole automobile. With the increasing demands of the automobile industry for light weight and high strength, the application of thin gauge (2.0-4.0 mm) girder steel is becoming more and more widespread. However, since the thin gauge steel sheet has low rigidity and sensitivity to process fluctuation during rolling, edge waves, middle waves, buckling, uneven thickness and other plate shape defects are very easy to generate, so that the product percent of pass is low, and the severe standard of the automobile industry is difficult to meet. In the prior art, the method for improving the plate shape focuses on local adjustment of the finish rolling process, such as optimizing the reduction distribution of last finishing mills, adjusting the roll bending force or the roll convexity, and the like. Although these methods have some effect, the profound effects of the rough rolling process on the final sheet shape are often ignored. If the rough rolling formed intermediate billet has the problems of uneven thickness, uneven temperature, concentrated internal stress and the like, the deformation resistance difference which is difficult to overcome is brought to the subsequent finish rolling process, and the intermediate billet becomes a fundamental cause of plate shape defects. In addition, the conventional rough rolling process is rough in pass arrangement and reduction distribution, lacks systematic collaborative design with the finish rolling process, and is difficult to adapt to the high-precision plate shape control requirement of the thin-specification girder steel. Therefore, a full-process and systematic rolling process optimization method from rough rolling to finish rolling is urgently needed to solve the technical problems of poor plate shape stability and low precision of thin-specification girder steel in the rolling process. The invention relates to a method for improving the shape of a thin girder steel, which has outstanding substantive characteristics and remarkable progress compared with the prior disclosed related patent technology, and the specific novelty is as follows: 1. The method is different from the method of the comparative patent 1 (CN 112077152B), wherein the method is characterized in that a 1+5 rolling mode is adopted in the core of the method, a 3+3 reversible rough rolling process of two frames is not clarified, the shape control depends on the final pass bending line shape and wedge shape adjustment, the reduction is not distributed as a core control means, the finish rolling is only carried out in a sectional convexity control mode, the linkage optimization design of the reduction and the shape is not carried out, and the method has insufficient pertinence to the thin girder steel. The invention takes reduction distribution as a core for the first time, adopts a process combination of two frames 3+3 reversible rough rolling and 7 frames finish rolling continuous rolling, distributes reduction according to the 'front 3 times of large reduction and the rear 3 times of even reduction', designs reduction strategies according to the 'F1-F3 large reduction and F4-F7 gradient reduction' in the finish rolling stage, forms full-flow reduction-plate shape closed-loop control from rough rolling to finish rolling, specially adapts 2.0-4.0mm thin girder steel, solves the technical pain points of easy occurrence of side waves and middle waves of thin products in the prior art, improves plate shape accuracy by more than or equal to 30 percent compared with the prior art, and is not seen in the comparison patent 1. 2. The difference from the comparison patent 2 (CN 113664048B) is that the comparison patent 2 discloses a method for judging and controlling the side turning of strip steel during the side pressing of a rough rolling vertical roll of a hot continuous rolling mill, and the technical core focuses on a vertical roll side pressing parameter adjustment and side turning judgment model, does not relate to the design of the reduction distribution of the two frames 3+3 reversible rough rolling, does not adopt the reduction cooperative strategy of 7 frames finish rolling continuous rolling, can only realize side turning control, and cannot improve the plate shape quality of thin girder steel in a targeted manner. The invention breaks through