Control method for preventing sidewise bending of longitudinally-cut split strips of hot-rolled coil

Abstract

The invention discloses a control method for preventing sidewise bending of longitudinal slitting of a hot-rolled coil. The control method comprises the steps of controlling the transverse thickness deviation of a steel plate and calculating the transverse center thickness variation requirement of the steel plate. The control method comprises the following steps that the steel plate inner side deformation amount is calculated according to the steel plate bending amount; calculating the thickness reduction of each steel plate under the action of tension according to the principle that the volumes of the steel plates are not changed before and after deformation; and calculating the transverse center thickness variation of the steel plate. The control method for preventing sidewise bending of longitudinal slitting of the hot-rolled coil plate is reasonable in design, the sidewise bending defect of slitting is effectively reduced by controlling the change of the transverse thickness of the steel plate, and the product quality of the steel plate is improved; according to the control method, additional treatment equipment is not needed, and the production cost is relatively low.

Description

Technical Field

[0001] The invention relates to the technical field of steel manufacturing, and in particular to a control method for preventing lateral bending of slit strips of hot-rolled coils. Background Art

[0002] At present, low-alloy high-strength wide and thick steel plates are generally produced by wide and thick plate mills, and the production process is: steelmaking-single-stand reversible rolling mill-cooling-hot straightening-shearing. Due to the high rolling speed, high efficiency and high yield rate of hot rolling production, low-alloy high-strength steel plates with a thickness between 7mm and 22mm are gradually replaced by hot rolling mills instead of wide and thick plate mills. The coils produced by hot rolling need to be further made into steel plates through cold straightening and shearing. The role of straightening is to straighten the coils by repeatedly bending the steel plates longitudinally, but it is difficult to eliminate transverse defects by straightening. Since transverse defects of steel plates are the main cause of the side bending defects of each strip after longitudinal cutting, they cannot be eliminated by straightening (such as Figure 1 shown).

[0003] To address these issues, existing approaches often involve increasing equipment investment. For example, patent CN110624959A, "A Leveling Method for Improving Side Bow Defects in Hot-Rolled High-Strength Strip," eliminates side bow defects by adding a leveling mill. Patent CN112845584A, "A Method for Effectively Controlling Side Bow in Slitting Hot-Rolled Strip," eliminates coil bow defects by increasing the finishing roll bending force and CVC roll profile. Some approaches, such as patent CN117840229A, "Hot Continuous Rolling Control Method for Resolving Side Bow Defects in Automotive Beam Steel Coils After Slitting," adjust process parameters to increase in-stock cooling time. However, these approaches increase equipment investment, production costs, and efficiency. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a control method for preventing the lateral bending of the longitudinally cut strips of hot-rolled coils, which effectively prevents the occurrence of lateral bending defects of the strips without increasing production costs.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The control method for preventing lateral bending of hot-rolled coil strips during longitudinal slitting is as follows: controlling the transverse thickness deviation of the steel plate and calculating the required transverse center thickness variation of the steel plate.

[0007] Further or preferred:

[0008] The control method comprises the following steps:

[0009] Calculate the inner deformation of the steel plate based on the bending amount of the steel plate;

[0010] Based on the principle that the volume of the steel plate remains unchanged before and after deformation, calculate the thickness reduction of each steel plate under tension;

[0011] Calculate the required change in the transverse center thickness of the steel plate.

[0012] In the control method, the width d of the steel strip, the length L and thickness H of the normal steel strip, the lateral bending amount Δx of the outer side of the steel plate after stripping, and the chord length Lw of the outer arc after the lateral bending are measured. The radius R of the outer arc is:

[0013] In the control method, the inner deformation of the steel plate is calculated based on the bending amount.

[0014] In the control method, the straightening process does not widen. According to the principle that the volume of the steel plate remains unchanged before and after deformation, the thickness reduction of each steel plate under the action of tension is:

[0015] In the control method, the change in the transverse center thickness of the steel plate is required to be: At this time, the transverse thickness is controlled according to the hot rolling requirements to prevent the steel plate from being bent during straightening and longitudinal slitting.

[0016] In the control method, the side bending amount after stripping is required to be ≤40mm.

[0017] In the control method, the steel coil is subjected to tension during the straightening process. When the inner side of the raw material is relatively thick, the deformation is large after straightening. The stored tensile elastic energy is released and rebounds after stripping to generate compressive stress, causing the steel plate to bend laterally to the outside. The side bending is controlled by changing the transverse thickness of the steel plate.

[0018] In the control method, the outer side of the steel plate is relatively thin, the deformation amount during straightening is small, the tensile elastic performance generated is small, and after being stripped, it is also affected by the inner stress and causes lateral bending to the outside. The lateral bending is controlled by changing the transverse thickness of the steel plate.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The control method for preventing lateral bending of longitudinally cut hot-rolled coil strips is reasonably designed. By controlling the change in the transverse thickness of the steel plate, the occurrence of lateral bending defects of the strips is effectively reduced, thereby improving the quality of the steel plate products. The control method does not require additional processing equipment and has a relatively low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is a brief description of the contents and symbols in the drawings of this specification:

[0022] Figure 1 This is a schematic diagram of the steel plate during straightening according to the present invention.

[0023] Figure 2 This is a schematic diagram of the steel plate after stripping according to the present invention.

[0024] Figure 3 Schematic diagram of the transverse thickness distribution of the steel plate of the present invention. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention will be further explained in detail below through description of embodiments with reference to the accompanying drawings.

[0026] like Figures 1 to 3 As shown, the control method for preventing lateral bending of the hot-rolled coil longitudinally cut strips is: controlling the transverse thickness deviation of the steel plate and calculating the required change in the transverse center thickness of the steel plate.

[0027] The preferred thickness control method comprises the following steps:

[0028] Calculate the inner deformation of the steel plate based on the bending amount of the steel plate;

[0029] Based on the principle that the volume of the steel plate remains unchanged before and after deformation, calculate the thickness reduction of each steel plate under tension;

[0030] Calculate the required change in the transverse center thickness of the steel plate.

[0031] The present invention analyzes the cause of lateral bending through the straightening principle and concludes that hot rolling is to control the transverse thickness deviation of the steel plate to prevent the occurrence of strip lateral bending defects.

[0032] In this thickness control method:

[0033] Depending on the scoliosis situation Figure 2 As shown, measure the strip width d of the steel plate, the length L and thickness H of the normal steel plate strip, the side bending amount Δx of the steel plate after the outer side strip, and the chord length Lw of the outer arc after the side bending, then the outer arc radius R:

[0034] According to the principles of elastic mechanics and straightening, the steel coil is subjected to tension during the straightening process. When the inner side of the raw material is thicker, the deformation is large after straightening, and the stored tensile elastic energy is released and rebounds after stripping to produce compressive stress, causing the steel plate to bend laterally. When the outer side of the steel plate is thinner, the deformation is small during straightening, and the tensile elastic energy generated is small. After stripping, it is also affected by the inner stress and bends laterally. The bending is controlled by changing the lateral thickness of the steel plate.

[0035] The present invention effectively reduces the occurrence of strip bending defects and improves the quality of steel plate products by controlling the change in the transverse thickness of the steel plate; and avoids uneven stress distribution after stripping due to local thickness deviation; and can also correct slight side bending through a straightening machine after stripping.

[0036] Further:

[0037] Calculate the inner deformation of the steel plate based on the bending amount The straightening process does not widen. According to the principle that the volume of the steel plate remains unchanged before and after deformation, the thickness reduction of each steel plate under the action of tension is: The required change in the transverse center thickness of the steel plate is calculated from this: At this time, the transverse thickness is controlled according to the hot rolling requirements to prevent the steel plate from being bent during straightening and longitudinal slitting.

[0038] The above analysis shows that the change in the transverse thickness of the steel plate is an important reason for the side bend after straightening and slitting. Therefore, based on the side bend data after slitting, the reasonable transverse thickness requirements of the hot-rolled steel plate can be obtained, thereby reducing the occurrence of side bend defects in the strips.

[0039] The requirement for the lateral bend after slitting is ≤40mm; the lateral bend of products processed by the thickness control method of the present invention after slitting meets the requirement; the requirement for the transverse thickness variation of the steel plate is calculated according to the formula, and specific examples are shown in the following table:

[0040]

[0041] The control method for preventing lateral bending of longitudinally cut strips of hot-rolled coils of the present invention is reasonably designed. By controlling the change in the transverse thickness of the steel plate, the occurrence of lateral bending defects of the strips is effectively reduced, thereby improving the quality of the steel plate products. The control method does not require additional processing equipment, and the production cost is relatively low.

[0042] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A control method for preventing lateral bending of hot rolled coil slitting strips, characterized by: The control method comprises: controlling the transverse thickness deviation of the steel plate and calculating the required variation of the transverse center thickness of the steel plate.

2. The control method for preventing lateral bending of hot-rolled coil slitting strips according to claim 1, characterized in that: The control method comprises the following steps: Calculate the inner deformation of the steel plate based on the bending amount of the steel plate; Based on the principle that the volume of the steel plate remains unchanged before and after deformation, calculate the thickness reduction of each steel plate under tension; Calculate the required change in the transverse center thickness of the steel plate.

3. The control method for preventing lateral bending of hot-rolled coil slitting strips according to claim 2, characterized in that: In the control method, the width d of the steel strip, the length L and thickness H of the normal steel strip, the lateral bending amount Δx of the outer side of the steel plate after stripping, and the chord length Lw of the outer arc after the lateral bending are measured. The radius R of the outer arc is:

4. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 3, characterized in that: In the control method, the inner deformation of the steel plate is calculated based on the bending amount.

5. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 4, characterized in that: In the control method, the straightening process does not widen. According to the principle that the volume of the steel plate remains unchanged before and after deformation, the thickness reduction of each steel plate under the action of tension is:

6. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 5, characterized in that: In the control method, the change in the transverse center thickness of the steel plate is required to be: At this time, the transverse thickness is controlled according to the hot rolling requirements to prevent the steel plate from being bent during straightening and longitudinal slitting.

7. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 6, characterized in that: In the control method, the side bending amount after stripping is required to be ≤40mm.

8. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 6, characterized in that: In the control method, the steel coil is subjected to tension during the straightening process. When the inner side of the raw material is relatively thick, the deformation is large after straightening. The stored tensile elastic energy is released and rebounds after stripping to generate compressive stress, causing the steel plate to bend laterally to the outside. The side bending is controlled by changing the transverse thickness of the steel plate.

9. The control method for preventing lateral bending of hot rolled coil slitting strips according to claim 8, characterized in that: In the control method, the outer side of the steel plate is relatively thin, the deformation amount during straightening is small, the tensile elastic performance generated is small, and after being stripped, it is also affected by the inner stress and causes lateral bending to the outside. The lateral bending is controlled by changing the transverse thickness of the steel plate.

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