Method for characterizing and judging section profile of hot-rolled strip steel

Abstract

The invention relates to a method for characterizing and judging the section contour of hot-rolled strip steel. The method comprises the following steps: S1, characterizing the length direction of the section contour of the strip steel through a convexity curve; wherein the convexity curve characterization standard is as follows: the convexity value range of the whole roll is 20-100 microns; s2, representing the width direction of the section contour of the strip steel through a cross section curve; wherein the characterization standard of the cross section curve is as follows: the head average curve and the through-roll average curve are taken as the judgment basis, and the effective convexity is defined as the vertical distance between the two side parts and the central point of the strip steel. According to the method, the overall actual characteristics of the section of the strip steel can be comprehensively reflected, and the contour quality is graded based on scientific and reasonable judgment rules, so that accurate characterization and rapid judgment of the section contour of the hot-rolled strip steel are realized, the strip steel quality condition is adjusted in time according to the actual condition of the section, and the production efficiency and the product quality are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot rolling strip process, and particularly relates to a method for characterizing and determining the cross-sectional profile of hot rolling strip. BACKGROUND

[0002] In the field of hot rolling strip production, the characterization and determination of the cross-sectional profile is a key link to ensure product quality. The cross-sectional profile not only affects the dimensional accuracy and flatness accuracy of the strip, but also directly determines its performance in subsequent processing.

[0003] However, the existing cross-sectional profile characterization and determination methods have many deficiencies, and there is no systematic quality determination method to ensure the quality of the cross-sectional profile of the product. Traditional methods mostly rely on manual measurement or simple optical detection equipment, and these methods can only provide limited size data and cannot fully reflect the complex shape characteristics of the cross-sectional profile of the strip, such as the edge shape and the overall shape of the cross-sectional profile. In addition, most existing methods lack effective determination criteria, making it difficult to accurately classify the cross-sectional profile, resulting in the inability to timely detect and correct cross-sectional profile deviations in the production process, thereby increasing the probability of producing defective and waste products.

[0004] With the increasing quality requirements of modern industry for hot rolling strip, it is particularly urgent to develop a method that can accurately characterize and quickly determine the cross-sectional profile using advanced measurement equipment. SUMMARY To solve the above problems, the present application provides a method for characterizing and determining the cross-sectional profile of hot rolling strip, which can fully reflect the overall actual characteristics of the cross-sectional profile of the strip and classify the profile quality based on scientific and reasonable determination rules, thereby achieving accurate characterization and quick determination of the cross-sectional profile of hot rolling strip, and timely adjusting the quality of the strip according to the actual situation of the cross-sectional profile, thereby improving production efficiency and product quality.

[0005] The technical solution adopted by the present application is as follows: The method for characterizing and determining the cross-sectional profile of hot rolling strip provided by the present application comprises the following steps: S1, characterizing the length direction of the cross-sectional profile of the strip by a crown curve; wherein the crown curve characterization standard is that the whole roll crown value range is 20-100 μm; S2, characterizing the width direction of the cross-sectional profile of the strip by a cross-sectional curve; wherein the cross-sectional curve characterization standard is that the average curve at the head and the average curve throughout the roll are used as the determination basis, and the effective crown is defined as the vertical distance between the center point of the strip and the connecting line of the two side edge reference points.

[0006] Further, in the step S1, the length of the crown value <40 μm does not exceed 1 / 3 of the length of the whole roll.

[0007] Further, in step S2, when the wedge of the strip steel is ≤15 μm, the strip steel crown ≈ effective crown; when the wedge of the strip steel is >15 μm, the effective crown < strip steel crown, at this time, the reference point of the effective crown is determined according to the curve shape of the edge portion.

[0008] Further, if the edge portion is smooth without obvious inflection points, the reference point is the relatively higher C40 on both sides; if there is an obvious inflection point in the edge portion thinning area, the reference point is the relatively higher inflection point on both sides.

[0009] Further, when the reference point is the relatively higher inflection point on both sides, the edge portion thinning area is not considered, and the height difference between adjacent points is <5-10 μm.

[0010] Further, when the reference point is the relatively higher inflection point on both sides, the effective crown is ≥40 μm and less than the wedge value of the strip steel.

[0011] Compared with the prior art, the present application has the following beneficial effects: 1. Improve product quality stability: Through accurate instrument detection and model calculation, the cross-sectional profile of hot-rolled strip steel can be accurately controlled to ensure that it always meets the standard parameter range. This precise control reduces the size deviation and shape defects caused by irregular cross-sectional shape, thereby significantly reducing the scrap rate and improving the overall quality stability of the product, providing customers with higher quality products.

[0012] 2. Improve production efficiency: Accurate detection and feedback data enable operators to quickly identify and adjust process parameters, reducing downtime adjustment time caused by cross-sectional profiles not meeting requirements. At the same time, through model parameter fitting calculation, the trend of cross-sectional profile change can be predicted in advance, and the rolling process parameter setting can be optimized to improve the continuity and stability of the production process, avoid production interruption, and significantly improve production efficiency.

[0013] 3. Enhance controllability of production process: Make accurate quality judgment according to the deviation degree of strip steel cross-sectional characteristic parameters from standard parameter range, and the fitting calculation of secondary model parameters can make more accurate prediction and optimization of cross-sectional profile, helping production personnel to take measures in advance to reduce production fluctuations caused by unexpected problems.

[0014] 4. Reduce production cost: By accurately controlling the cross-sectional profile, reduce the waste of raw materials caused by size deviation or shape defects, and improve the first-time pass rate of raw materials. At the same time, the optimized rolling process parameters can reduce unnecessary rolling times and adjustment time, reduce energy consumption, thereby effectively reducing production cost and improving the economic benefit of enterprises.

[0015] 5. Promote the intellectualization of the production process: according to the product quality standard summarized by the instrument detection section profile, it can be combined with model calculation to provide rich data support for the production process, so that the production decision is more scientific and reasonable, and the production process is promoted to the intelligent direction. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 It is a convexity curve determination standard diagram in the application; Fig. 2 It is a schematic diagram of the height difference of adjacent points without considering the edge thinning area (the dashed line is 10 μm per grid). Fig. 3 It is a schematic diagram of the effective convexity representation (the relative high inflection point is taken as the reference point). DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0018] The hot-rolled strip section profile is generated in the rolling process, which belongs to process quality control. Due to the characteristics of high temperature and high speed rolling in hot rolling production, the detection and feedback data of the instrument and the fitting calculation of the secondary model parameters are particularly important for the control of the hot-rolled section profile. The accuracy of instrument detection directly affects the control of the section profile, and the data feedback of the instrument also affects the identification of the section profile by the model. Specifically, the accuracy of instrument detection will directly affect the control effect of the section profile, because only accurate detection data can provide reliable basis for subsequent control. At the same time, the data feedback of the instrument will also affect the identification of the section profile by the model, and accurate data feedback is helpful for the model to more accurately identify the actual state of the section profile. Based on these detection and feedback data, the control strategy of the section profile can be further optimized through the fitting calculation of the secondary model parameters. On this basis, in order to more scientifically evaluate the quality of the section profile, different judgment levels can be set according to the deviation degree of the strip section characteristic parameters from the standard parameter range. In this way, not only the section profile can be more accurately controlled, but also the quality level can be effectively evaluated, so as to realize the fine management of the quality in the production process of hot-rolled strip.

[0019] Referring to the accompanying Figs. 1-3 The method for representing and determining the section profile of hot-rolled strip provided by the application specifically includes the following steps: S1, representing the length direction of the strip section profile by the convexity curve; Convexity (i.e. length direction) representation standard: the whole roll convexity value range is 20~100μm, the length of convexity value <40μm is not more than 1 / 3 of the whole roll length; S2, the width direction of the strip cross-section profile is represented by the cross-section curve; The cross-section (i.e. width direction) representation standard is: taking the head average curve (Part 1) and the whole roll average curve as the judgment basis, the effective convexity is defined as the vertical distance between the two side edge reference point connecting line and the strip center point; when the strip wedge is ≤15μm, the strip convexity ≈ effective convexity; when the strip wedge is >15μm, the effective convexity <strip convexity, at this time, the reference point of the effective convexity can be determined according to the shape of the edge curve, such as the edge is smooth without obvious inflection point, the relatively higher C40 on both sides can be used as the reference point; if there is an obvious inflection point in the edge thinning area, the relatively higher inflection point on both sides is used as the reference point, and the specific standard is as follows: Without considering the edge thinning area, the height difference between adjacent points is <5~10μm; The effective convexity is ≥40μm and less than the strip wedge value; Studies have shown that the convexity, wedge (i.e. unevenness in the width direction) and local high point (i.e. local protrusion) of hot-rolled strip have a significant impact on the shape, defects (such as bulge, raised rib) and other defects in the cold rolling process. The three are interrelated geometric parameters, and controlling the reasonable range of the convexity, wedge and local high point of hot-rolled strip can effectively reduce the defects such as bulge and raised rib in the cold rolling process.

[0020] In actual production, the hot-rolled convexity is generally controlled at 0~0.06mm, and under normal circumstances, the shape will be improved after cold rolling and straightening, but in the actual rolling process, the transverse distribution of the strip shape has different deformation tensile strengths, and different degrees of deformation heat are generated in the deformation process, thereby affecting the finished product shape after cold rolling. Studies have shown that when the hot-rolled raw material convexity decreases, the shape value gradually decreases, the edge of the strip appears to be upturned, and after multiple superposition, the edge bulge defect appears; within a certain range, the hot-rolled raw material convexity increases, and the shape gradually flattens; but when the hot-rolled raw material convexity value is too large, the strip is prone to intermediate bulge defects.

[0021] The hot-rolled raw material wedge is closely related to the control of the shape, when the hot-rolled raw material has a certain wedge, i.e. the thickness of the strip on both sides is not consistent, thereby causing the bearing roll gap to deviate from the set target, eventually causing the rolling force to be applied asymmetrically, forming a shape defect. Studies have shown that when the hot-rolled raw material wedge is 15μm, the wave shape still exists, but it basically meets the actual field demand, and the larger the wedge, the worse the shape, and vice versa, the smaller the wedge, the better the shape. At the same time, the convexity is required to be greater than the wedge, so as to ensure that there is no bulge defect after cold rolling.

[0022] The influence of the local high point of the hot-rolled raw material on the shape of the cold-rolled plate exists only in the area near the high point, and the local high point after rolling will be reduced but not disappeared. Studies have shown that when the local high point is less than or equal to 0.006mm, it has no obvious influence on the shape of the cold-rolled plate; when the local high point increases to 0.01mm, obvious waves appear at the high point position, and the finished steel coil has a bulging defect.

[0023] The method of the present application relies on advanced instruments to provide accurate cross-sectional profile curves, and the three technical indicators of crown, wedge and local high point, which are commonly used to represent the shape, are represented in a quantitative manner on the cross-sectional profile curves. Not only can the cross-sectional profile be more accurately controlled, but the quality level can also be effectively evaluated, and the fine management of the cross-sectional profile in the production process of hot-rolled strip steel can be realized.

[0024] The details of the present application are all known technologies.

[0025] The above-described embodiments are merely preferred embodiments of the present application and do not limit the scope of the present application. Various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A method for characterizing and determining the cross-sectional profile of hot-rolled strip steel, characterized in that, The method includes the following steps: S1. The convexity curve characterizes the length direction of the strip cross-section profile; the standard for the convexity curve is: the convexity value of the whole roll is in the range of 20 to 100 μm; S2. The width direction of the strip profile is represented by the cross-sectional curve; the standard for the cross-sectional curve is: based on the average curve of the head and the average curve of the whole roll, the effective convexity is defined as: the perpendicular distance between the line connecting the reference points on both sides and the center point of the strip.

2. The method for characterizing and determining the cross-sectional profile of hot-rolled strip steel according to claim 1, characterized in that: In step S1, the length with a convexity value < 40 μm does not exceed 1 / 3 of the total roll length.

3. The method for characterizing and determining the cross-sectional profile of hot-rolled strip steel according to claim 1, characterized in that: In step S2, when the wedge shape of the strip is ≤15μm, the strip crown is approximately equal to the effective crown; when the wedge shape of the strip is >15μm, the effective crown is less than the strip crown. In this case, the reference point for the effective crown is determined based on the shape of the edge curve.

4. The method for characterizing and determining the cross-sectional profile of hot-rolled strip steel according to claim 3, characterized in that: If the edge is smooth and there is no obvious inflection point, the C40 of the two sides that is relatively higher is used as the reference point; if there is an obvious inflection point in the thinning area of ​​the edge, the inflection point of the two sides that is relatively higher is used as the reference point.

5. The method for characterizing and determining the cross-sectional profile of hot-rolled strip steel according to claim 4, characterized in that: When taking the relatively higher inflection points on both sides as reference points, without considering the thinning zone at the edges, the height difference between adjacent points is <5~10μm.

6. The method for characterizing and determining the cross-sectional profile of hot-rolled strip steel according to claim 5, characterized in that: When the relatively high inflection points on both sides are taken as reference points, the effective convexity is ≥40μm and less than the wedge value of the strip steel.

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