Rolling method for ultrapure ferrite precision strip steel of four-stand-column twenty-high-roll mill
By optimizing the rolling process of the 20-roll four-column rolling mill, the surface quality problem of ultra-pure ferrite precision strip steel is solved, and the effects of surface chromatic aberration elimination, roughness reduction, gloss improvement and head-tail surface consistency are achieved.
Patent Information
- Application Number
- CN202510051468.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-04-11
AI Technical Summary
When producing ultrapure ferrite precision strip steel, surface quality problems are often encountered, such as uneven color, longitudinal color difference, large differences in roughness and gloss, and inconsistent surfaces at the head and tail.
By optimizing the rolling process of the twenty-roll four-column rolling mill, including the selection of materials of specific thickness and hardness, and the use of rolling rolls of different roughness and laser burping rolls, the rolling speed and oil flow rate are controlled to ensure the accurate parameters of each rolling passage.
It has achieved the elimination of the surface color difference of steel strips, reduced surface roughness, improved surface gloss, and ensured consistency of the head and tail surfaces, meeting the strict requirements of the high-end market for ultra-pure ferrite stainless steel surfaces.
Smart Images
Figure CN119794085A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of metal material processing, and is a method for rolling ultrapure ferrite precision strip steel using a twenty-roller four-column rolling mill. The method eliminates the color difference on the surface of the steel strip, reduces the surface roughness, improves the surface gloss, and achieves the effect of consistent head and tail surfaces by optimizing the rolling process. Background Art
[0002] Ultra-pure ferritic stainless steel materials used in automotive decorative strips, such as 430MA, J442D, B442D, 439M, SUS444, etc., have relatively high contents of elements such as Cr, Nb, and Si. This makes it difficult to control the purity and surface quality of the materials in the steelmaking and continuous casting processes. At present, the high-end market has extremely high requirements for the surface of ultra-pure ferritic stainless steel used in automotive decorative strips, because its final use surface is a flat surface after bright annealing (BA treatment), which can be called the most demanding material among surface-type stainless steels. When producing ultra-pure ferritic precision strip steel by conventional rolling process, many problems are often encountered, such as poor surface quality, which is manifested as uneven surface color, longitudinal color difference, and large differences in roughness and glossiness of the head and tail surfaces. With the continuous development of science and technology, the market demand for ultra-pure ferritic precision strip steel is increasing day by day, and a rolling method that can effectively improve product quality is urgently needed. Although the existing twenty-high rolling mill has certain advantages in plate shape control, its rolling process still needs to be further optimized in the production process of ultra-pure ferrite precision strip.
[0003] The present invention eliminates the color difference of the steel strip surface, reduces the surface roughness, improves the surface gloss, and achieves the effect of consistent head and tail surfaces by optimizing the rolling process. Summary of the invention
[0004] The purpose of the present invention is to provide a method for rolling ultra-pure ferrite precision strip steel using a four-column twenty-high rolling mill in order to solve the above-mentioned problems.
[0005] The object of the present invention is achieved as follows: A method for rolling ultrapure ferrite precision strip steel by a four-column twenty-high rolling mill, comprising the following steps: Step 1: Select ultrapure ferrite material after cold-rolled pickling surface with a thickness of 0.8mm, a thickness tolerance of ±30μm, a width of 600-620mm, and a hardness of 160-180hv; Step 2: Use two intermediate free rolls with a convexity of 0.5mm and a tolerance of ±10μm, and roll for 7 passes; Step 3: Use a laser texturing roll H roll with a diameter of 30-32mm and a roughness Ra of 1.0-1.2μm to open the blank in the first pass, and control the rolling speed at 190-200m / min and the rolling oil flow rate at 750-850L / min; Step 4: Use a laser texturing roll H roll with a diameter of 30-32mm and a roughness Ra of 1.0-1.2μm to open the blank in the second to fifth passes, and control the rolling speed at 190-200m / min and the rolling oil flow rate at 750-850L / min; Step 5: Use a laser texturing roll H roll with a diameter of 30-32mm and a roughness Ra of 1.0-1.2μm to open the blank in the second to fifth passes, and control the rolling speed at 190-200m / min and the rolling oil flow rate at 750-850L / min; Step 6: Use a laser texturing roll H roll with a diameter of 30-32mm and a roughness Ra of 1.0-1.2μm to open the blank in the first pass, and control the rolling speed at 190-200m / min and the rolling oil flow rate at 750-850L / min. The rolling is carried out using the M roller with a diameter of 30-32mm and a roughness Ra of 0.3-0.5μm, the rolling oil flow rate is controlled at 600-700L / min, and the rolling speed is controlled at 400-450m / min; Step five: The 6th pass uses the D roller with a diameter of 30-32mm and a roughness Ra of 0.07-0.1μm, the rolling speed is controlled at 140-150m / min, and the rolling oil flow rate is controlled at 450-550L / min; Step six: The 7th pass uses the P roller with a diameter of 30-32mm and a roughness Ra of 0.03-0.05mm, the rolling speed is controlled at 240-250m / min, and the rolling oil flow rate is controlled at 450-550L / min.
[0006] The second intermediate free roller in step 2 has a cone length of 130 mm and a tolerance of ±5 mm; a cone height of 0.21 mm and a tolerance of ±10 μm; that is, an intermediate roller with a taper of 130*0.21.
[0007] The beneficial effect of the present invention is that the method uses the H roller in the first pass to break the morphology of visible defects on the surface so that the defects can be completely eliminated in the subsequent rolling passes. The D roller is used in the pre-finished pass to reduce the surface roughness and glossiness of the steel strip. The P roller is used in the finished pass to ensure that the surface roughness Ra of the steel strip is within 0.05-0.1μm, the brightness is above 400GU, and the brightness and roughness are stable at the beginning and end. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will be further described below in conjunction with the accompanying drawings.
[0009] Figure 1 This is a surface morphology diagram after H-roll rolling used in the present invention.
[0010] After rolling with H-rollers, visible defects such as surface color difference and uneven color are eliminated. In addition, due to the high surface roughness, the oil film thickness between the roll and the steel strip is increased, eliminating the roll sticking phenomenon during the rolling process. DETAILED DESCRIPTION
[0011] According to customer requirements, determine the thickness of finished rolling material and select the roll system of the rolling mill. Determine the roll system crown, taper, work roll type, roughness, diameter, tolerance and other requirements.
[0012] The present invention eliminates the color difference of the steel strip surface, reduces the surface roughness and improves the surface gloss by optimizing the rolling process. 1. Use a high-roughness laser texturing roller to open the blank to break the surface structure of the steel strip, thereby eliminating the color difference of the raw material. 2. Use a low-roughness roller before the finished product to improve the surface roughness and brightness consistency of the finished product. 3. Use a polishing roller to reduce the surface roughness and brightness.
[0013] This method stabilizes the surface roughness Ra of the finished steel strip between 0.08-0.1μm, controls the brightness between 400-450GU, and stabilizes the roughness and brightness of the head and tail, meeting the surface technical requirements.
[0014] 1. Select cold-rolled pickled surface ultra-pure ferrite material with a thickness of 0.8mm, a width of 600-620mm, and a hardness of 160-180hv.
[0015] 2. Use a free roll with a crown of 0.5 mm and an intermediate roll with a taper of 130*0.21 mm, and roll in 7 passes.
[0016] 3. In the first pass, a laser texturing roller H with a diameter of 30-32 mm and a roughness Ra of 1.0-1.2 μm is used to open the blank. The rolling speed is controlled within 200 m / min, and the rolling oil flow is controlled at 750-850 L / min to break the surface passivation layer and eliminate surface color difference.
[0017] 4. Use a roller M with a diameter of 30-32 mm and a roughness Ra of 0.3-0.5 μm to roll the 2nd to 5th passes, and control the rolling oil flow rate at 600-700 L / min.
[0018] 5. Use roller D with a diameter of 30-32 mm and a roughness Ra of 0.07-0.1 μm to roll the 6th pass. The rolling speed is controlled within 150 m / min and the rolling oil flow is controlled at 450-550 L / min to reduce the surface roughness of the steel strip and facilitate the stability of the surface quality of the steel strip in the subsequent rolling process.
[0019] 6. Use a P roller with a diameter of 30-32 mm and a roughness Ra of 0.03-0.05 μm for the seventh rolling pass. The rolling speed is controlled within 250 m / min and the rolling oil flow is controlled at 450-550 L / min to further reduce the surface roughness, improve the brightness, and make the surface quality of the head and tail of the steel strip consistent.
[0020] 7. The specific rolling process table is as follows.
[0021] Example 1
[0022] 1. Select ultra-pure ferritic stainless steel with a pickling surface, hardness of 160-180Hv, thickness of 0.8mm, width of 600mm, and grade 439M. Use a free roll with a convexity of 0.5mm and an intermediate roll with a taper of 130*0.21mm, and roll in 7 passes.
[0023] 2. In the first pass, a laser texturing roll H roll with a diameter of 30-32 mm and a roughness Ra of 1.0-1.2 μm is used to open the blank. The rolling speed is controlled within 200 m / min and the rolling oil flow rate is controlled at 750-850 L / min.
[0024] 3. Use a roller M with a diameter of 30-32 mm and a roughness Ra of 0.3-0.5 μm to roll the 2nd to 5th passes, and control the rolling oil flow rate at 600-700 L / min.
[0025] 4. Use roller D with a diameter of 30-32 mm and a roughness Ra of 0.07-0.1 μm to roll the 6th pass. The rolling speed is controlled within 150 m / min and the rolling oil flow rate is controlled at 450-550 L / min.
[0026] 5. Use a roller P roller with a diameter of 30-32mm and a roughness Ra of 0.03-0.05μm to roll the seventh pass. The rolling speed is controlled within 150m / min, and the rolling oil flow is controlled at 450-550L / min.
[0027] Example 2
[0028] 1. Select the ultra-pure ferrite stainless steel of grade SUS444 with pickling surface, hardness 160-180Hv, thickness 0.8mm, width 620mm. Use a free roll with a convexity of 0.5mm and an intermediate roll with a taper of 130*0.21mm, and roll in 7 passes.
[0029] 2. In the first pass, a laser texturing roll H roll with a diameter of 30-32 mm and a roughness Ra of 1.0-1.2 μm is used to open the blank. The rolling speed is controlled within 200 m / min and the rolling oil flow rate is controlled at 750-850 L / min.
[0030] 3. Use a roller M with a diameter of 30-32 mm and a roughness Ra of 0.3-0.5 μm to roll the 2nd to 5th passes, and control the rolling oil flow rate at 600-700 L / min.
[0031] 4. Use roller D with a diameter of 30-32 mm and a roughness Ra of 0.07-0.1 μm to roll the 6th pass. The rolling speed is controlled within 150 m / min and the rolling oil flow rate is controlled at 450-550 L / min.
[0032] 5. Use a roller P roller with a diameter of 30-32mm and a roughness Ra of 0.03-0.05μm to roll the seventh pass. The rolling speed is controlled within 150m / min, and the rolling oil flow is controlled at 450-550L / min.
[0033]
[0034] The above description is only a specific embodiment of the present invention, but the structural features of the protection scope of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are all covered by the patent scope of the present invention.
Claims
1. A method for rolling ultrapure ferrite precision strip steel using a four-column twenty-high rolling mill, characterized in that: The following steps are involved: Step 1: Select ultra-pure ferrite material after cold-rolled pickling surface with a thickness of 0.8mm, a thickness tolerance of ±30μm, a width of 600-620mm, and a hardness of 160-180hv; Step 2: Use two intermediate free rolls with a crown of 0.5 mm and a tolerance of ±10 μm, and roll for 7 passes; Step 3: In the first pass, a laser texturing roll H roll with a diameter of 30-32 mm and a roughness Ra of 1.0-1.2 μm is used to open the blank. The rolling speed is controlled at 190-200 m / min and the rolling oil flow rate is controlled at 750-850 L / min. Step 4: For the 2nd to 5th passes, a roller M with a diameter of 30-32 mm and a roughness Ra of 0.3-0.5 μm is used for rolling, and the rolling oil flow rate is controlled at 600-700 L / min, and the rolling speed is controlled at 400-450 m / min; Step 5: The sixth pass is rolled using a roller D with a diameter of 30-32 mm and a roughness Ra of 0.07-0.1 μm, the rolling speed is controlled at 140-150 m / min, and the rolling oil flow rate is controlled at 450-550 L / min; Step six: For the 7th pass, use a roller P with a diameter of 30-32 mm and a roughness Ra of 0.03-0.05 mm for rolling. The rolling speed is controlled at 240-250 m / min, and the rolling oil flow rate is controlled at 450-550 L / min.
2. The method for rolling ultrapure ferrite precision strip steel by a four-column twenty-high rolling mill according to claim 1, characterized in that: The second intermediate free roller in step 2 has a cone length of 130 mm and a tolerance of ±5 mm; a cone height of 0.21 mm and a tolerance of ±10 μm; that is, an intermediate roller with a taper of 130*0.21.