A method of cold rolling an if steel

Abstract

This invention relates to a cold rolling method for IF steel, belonging to the technical field of control equipment or methods specifically applicable to metal rolling mills or their processed products. The method first sets an appropriate elongation rate for the strip using a leveler, then precisely calculates and controls the pickling speed based on the strip's width, thickness, and the heating capacity of the acid solution graphite heater. After pickling, just before entering cold rolling, appropriate loads and tensions are set for each stand to prevent abrupt changes in rolling force during rolling, ensuring stability during cold rolling. Furthermore, the forward slip value of stand 5 is monitored in real time, and the forward tension of stand 5 is adjusted in real time to prevent strip breakage and steel accumulation. The parameter control at each stage of strip processing significantly improves the stability of IF steel during cold rolling.

Description

Technical Field

[0001] This invention relates to a cold rolling method for IF steel, belonging to the technical field of control equipment or methods specifically applicable to metal rolling mills or their processed products (B21B37 / 00). Background Technology

[0002] Hot-rolled strip steel is rolled and coiled at high temperatures, resulting in the formation of iron oxide scale on its surface, which firmly covers the strip. If this iron oxide-covered strip steel is directly sent to a cold rolling mill, it will not only severely affect the surface quality and processing performance of the cold-rolled sheet, but also damage the expensive, low-roughness cold-rolling rolls. Therefore, the deoxidation process before cold rolling is crucial. Typically, strip steel undergoes straightening and pickling before cold rolling. Inappropriate straightening elongation will not only fail to completely break up the iron oxide scale on the strip surface, but will also damage the strip surface, thus affecting the pickling effect. Currently, the pickling speed before cold rolling is mainly determined by looking up a static table. Pickling speed levels are assigned according to the steel grade, thickness levels are divided according to the steel grade's thickness range, and similarly, width levels are divided according to the steel grade's width range. A pickling speed setting value is then found in the static table based on the pickling speed level, thickness level, and width level. This manually selected pickling speed is not precise enough, and similar specifications often use the same pickling speed, making it unsuitable for the production of IF steel, which requires high surface quality after pickling.

[0003] When IF steel is rolled at constant speed on the cold rolling mill, the cold rolling deformation reaches 90%. Abnormal fluctuations in rolling force and tension duration occur at stand 1, with large tension fluctuations at the entrance of stand 1, sometimes resulting in significant thickness differences, severely impacting production stability. The cause is attributed to the relatively soft nature of IF steel, with a yield strength of around 200 MPa. Furthermore, compared to stands 2-5, stand 1 represents the first hardening of the hot-rolled material, leading to frequent fluctuations in rolling force. Meanwhile, during the cold rolling process at stand 5, the rolls gradually become smoother, causing backward slippage and posing a risk of strip breakage and steel accumulation. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to improve the stability of IF steel during cold rolling.

[0005] The technical solution proposed by this invention to solve the above-mentioned technical problems is: a cold rolling method for IF steel, comprising the following steps: Step 1: After hot rolling, the strip steel is straightened by a tension leveler, with the elongation of the tension leveler set at 1±0.2%; Step 2: After the strip steel is straightened by the tension leveler, it enters the pickling process. The pickling speed v is controlled according to the pickling speed v calculated by the following formula (1). v=p÷60÷y÷h÷w (1) In formula (1): p is the known heating capacity of the acid graphite heater; y is the specific gravity of steel; h is the known strip thickness; w is the known strip width; Step 3: After pickling, the strip enters the cold continuous rolling mill. Set the tension for each stand. The front tension of stand 5 is set smaller than that of stand 4. Set the front tension of stand 1 to (50±5) N / mm. 2 The tension at the front of frame 2 is set to (100±5) N / mm. 2 The tension of frame 3 is set to (110±5) N / mm. 2 The tension in front of frame 4 is set to (110±5) N / mm. 2 The tension of frame 5 is set to (80±5) N / mm. 2 The tension of frame 5 is set to (55±5) N / mm. 2 ; Set the load for each rack: Set the load for rack 1 to 37.0±1.0%, the load for rack 2 to 41.0±1.0%, the load for rack 3 to 38.0±1.0%, the load for rack 4 to 33.0±1.0%, and the load for rack 5 to 34.0±1.0%. Step 4: During actual rolling, read the forward slip value of stand 5 in real time; when the forward slip value is greater than -1%, the forward tension of stand 5 is reduced by 20%; when the forward slip value is between -1% and 0%, the forward tension of stand 5 is reduced by 10%.

[0006] The beneficial effects of this invention are as follows: First, since the pickling speed is calculated based on dynamic cold rolling parameters (strip thickness and width, etc.), the pickling process can be more precisely controlled according to this calculation, improving the surface quality of the IF steel and avoiding residual pickling marks on the IF steel surface. Second, by setting the elongation of the tension leveler at 1±0.2%, the iron oxide scale on the IF steel surface can be completely broken without damaging the IF steel. Third, by setting appropriate stand load and stand tension, the IF steel is rolled stably during cold rolling. Furthermore, by monitoring the forward slip value of stand 5 in real time and adjusting the forward tension in real time, the risk of strip breakage and steel accumulation can be reduced. Detailed Implementation

[0007] Example

[0008] This embodiment of a cold rolling method for IF steel includes the following steps: Step 1: After hot rolling, the strip steel is straightened by a tension leveler, with the elongation set at 0.95%. Step 2: After the strip steel is straightened by the tension leveler, it enters the pickling process. The pickling speed v is controlled according to the pickling speed v calculated by the following formula (1). v=p÷60÷y÷h÷w (1) In equation (1): the known heating capacity of the acid-graphite heater is p = 160 tons / hour, i.e.; the specific gravity of steel is y = 7.85 g / m³. 3 The known strip thickness h = 2.6 mm; the known strip width w = 1205 mm; The calculation yields v = 160 * 1000000 ÷ 60 ÷ 7.85 ÷ 2.6 ÷ 1205 ≈ 108 m / min; therefore, the pickling speed should be controlled at 108 m / min. Step 3: After pickling, the strip enters the cold continuous rolling mill. Set the tension for each stand. The front tension of stand 5 is set to be smaller than that of stand 4. Set the front tension of stand 1 to 48 N / mm. 2 The tension of frame 2 is set to 98 N / mm. 2 The tension of frame 3 is set to 109 N / mm. 2 The tension in front of frame 4 is set to 110 N / mm. 2 The tension of frame 5 is set to 85 N / mm. 2 The tension of frame 5 is set to 60 N / mm. 2 ; Set the load for each rack: Set the load for rack 1 to 36.8%, rack 2 to 40.8%, rack 3 to 37.4%, rack 4 to 32.8%, and rack 5 to 33.6%. Step 4: During actual rolling, the forward slip value of stand 5, read in real time, is -1.025 > -1, and the forward tension of stand 5 is reduced by 20% to 68 N / mm. 2

[0009] Example

[0010] This embodiment of a cold rolling method for IF steel includes the following steps: Step 1: After hot rolling, the strip steel is straightened by a tension leveler, with the elongation set at 1.12%. Step 2: After the strip steel is straightened by the tension leveler, it enters the pickling process. The pickling speed v is controlled according to the pickling speed v calculated by the following formula (1). v=p÷60÷y÷h÷w (1) In equation (1): the known heating capacity of the acid-graphite heater is p = 160 tons / hour; the specific gravity of steel is y = 7.85 g / m³. 3 The known strip thickness h = 2.6 mm; the known strip width w = 1005 mm; The calculation yields v = 160 * 1000000 ÷ 60 ÷ 7.85 ÷ 2.6 ÷ 1005 ≈ 130 m / min. Therefore, the pickling speed should be controlled at 130 m / min. Step 3: After pickling, the strip enters the cold continuous rolling mill. Set the tension for each stand, with the front tension of stand 5 being lower than that of stand 4; set the front tension of stand 1 to 52 N / mm. 2 The tension of frame 2 is set to 102 N / mm. 2 The tension of frame 3 is set to 113 N / mm. 2 The tension in front of frame 4 is set to 115 N / mm. 2 The tension of frame 5 is set to 75 N / mm. 2 The tension of frame 5 is set to 54 N / mm. 2 ; Set the load for each rack: Set the load for rack 1 to 37.6%, rack 2 to 41.4%, rack 3 to 38.8%, rack 4 to 33.8%, and rack 5 to 34.2%. Step 4: During actual rolling, the forward slip value of stand 5, read in real time, is -0.142. Since the forward slip value is between -1% and 0%, the forward tension of stand 5 is reduced by 10% to 67.5 N / mm. 2 .

[0011] Example

[0012] This embodiment of a cold rolling method for IF steel includes the following steps: Step 1: After hot rolling, the strip steel is straightened by a tension leveler, with the elongation rate of the tension leveler set at 1%. Step 2: After the strip steel is straightened by the tension leveler, it enters the pickling process. The pickling speed v is controlled according to the pickling speed v calculated by the following formula (1). v=p÷60÷y÷h÷w (1) In equation (1): the known heating capacity of the acid-graphite heater is p = 160 tons / hour; the specific gravity of steel is y = 7.85 g / m³. 3 The known strip thickness h = 2.6 mm; the known strip width w = 1105 mm; The calculation yields v = 160 * 1000000 ÷ 60 ÷ 7.85 ÷ 2.6 ÷ 1105 ≈ 118 m / min. Therefore, the pickling speed should be controlled at 118 m / min. Step 3: After pickling, the strip enters the cold continuous rolling mill. Set the tension for each stand, with the front tension of stand 5 being lower than that of stand 4; set the front tension of stand 1 to 50 N / mm. 2 The tension of frame 2 is set to 100 N / mm. 2 The tension of frame 3 is set to 110 N / mm. 2 The tension in front of frame 4 is set to 110 N / mm. 2 The tension of frame 5 is set to 80 N / mm. 2The tension of frame 5 is set to 55 N / mm. 2 ; Set the load for each rack: Set the load for rack 1 to 37%, rack 2 to 41%, rack 3 to 38%, rack 4 to 33%, and rack 5 to 34%. Step 4: In actual rolling, the forward slip value of stand 5 read in real time is 0.51 > 0, so the forward tension of stand 5 does not need to be adjusted.

[0013] The above description is only a preferred embodiment of the present invention, but the present invention is not limited thereto. All equivalent substitutions or modifications made to the concepts and technical solutions of the present invention should be covered within the protection scope of the present invention.

Claims

1. A cold rolling method for IF steel, characterized in that... Includes the following steps: Step 1: After hot rolling, the strip steel is straightened by a tension leveler, with the elongation of the tension leveler set at 1±0.2%; Step 2: After the strip steel is straightened by the tension leveler, it enters the pickling process. The pickling speed v is controlled according to the pickling speed v calculated by the following formula (1). v=p÷60÷y÷h÷w (1) In formula (1): p is the known heating capacity of the acid graphite heater; y is the specific gravity of steel; h is the known strip thickness; w is the known strip width; Step 3: After pickling, the strip enters the cold continuous rolling mill. Set the tension for each stand, with the front tension of stand 5 being lower than that of stand 4; set the front tension of stand 1 to 50±5 N / mm. 2 The tension at the front of frame two is set to 100±5 N / mm. 2 The frame tension is set to 110±5 N / mm. 2 The tension at the front of the four sides of the frame is set to 110±5 N / mm. 2 The tension of frame five is set to 80±5 N / mm. 2 The tension of frame five is set to 55±5 N / mm. 2 ; Set the load for each rack: Set the load for rack 1 to 37.0±1.0%, rack 2 to 41.0±1.0%, rack 3 to 38.0±1.0%, rack 4 to 33.0±1.0%, and rack 5 to 34.0±1.0%. Step 4: During actual rolling, read the forward slip value of stand 5 in real time; when the forward slip value is greater than -1%, the forward tension of stand 5 is reduced by 20%; when the forward slip value is between -1% and 0%, the forward tension of stand 5 is reduced by 10%.