A method for improving the stability of the weld zone in a four-stand cold continuous rolling mill

Abstract

This invention discloses a method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill, relating to the technical field of cold continuous rolling mills. The specific operations of this method are as follows: S1, determine the influence of the strip cross-sectional stress distribution during the weld seam process, including: strip shape, F3 roll shape, and bending roll force; S2, by analyzing the fluctuation range and amplitude of the F3 rolling force during the weld seam process, rationally determine the automatic bending roll force compensation value for the F3 work roll. This method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill eliminates stress concentration at the edge or center of the strip by employing an automatic compensation bending roll process during weld seam rolling in the four-stand continuous rolling mill, improving rolling stability, reducing the probability of cavity opening and edge cracking accidents, and simultaneously calculating the bending roll force compensation model corresponding to the change in the small diameter F3 roll force in the four-stand continuous rolling mill, incorporating automatic program control, and enhancing the degree of mechanization.

Description

Technical Field

[0001] This invention relates to the field of cold rolling mill technology, specifically to a method for improving the stability of the weld seam area in a four-stand cold rolling mill. Background Technology

[0002] In response to changes in steel grade specifications, roll position, rolling force, and roll diameter (including the small roll diameter of the three stands), the 1720 rolling mill uses the actual plate shape between each stand as a basis for determining the level of bending roll force in conjunction with the target plate shape requirements. Special attention is paid to the control level of bending roll force of the small roll diameter of the F3 stand work roll. Since the 1720 continuous rolling mill unit was upgraded in 2021, the roll diameter values ​​of the three stands have been significantly reduced. Consequently, under the corresponding stable rolling conditions, the overall bending roll control ratio should decrease accordingly.

[0003] Under stable high-speed rolling conditions, the bending roll force is basically matched with the rolling force level; especially for thin-gauge rolling, micro-edge waviness control must be considered at the exit of the third stand; in the low-speed weld seam area, as the rolling force increases, the bending roll force must be compensated quickly and proportionally to achieve a reasonable bending roll level to ensure the straightness of the sheet between stands. Inappropriate bending roll settings or improper adjustments can lead to poor sheet shape, causing cavitation or edge tearing.

[0004] In the existing technology, the roll profiles of each stand of the UCMW type four-stand rolling mill have undergone significant changes: the work rolls and intermediate rolls of the F1 and F2 stands have the function of lateral movement and the work rolls have a convex roll profile. The work roll diameter of the F3 stand has been modified to a small roll diameter (300-340mm). The internal stress changes of the strip are extremely sensitive to the changes in the bending roll force of the F3 stand. When rolling thin specifications through the weld, if the bending roll force is controlled too high, it is easy to cause the edge to tear and break the strip; if the bending roll force is controlled too low, it is easy to cause the strip to open up. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill, thus solving the problems existing in the prior art.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill, the specific operation of which is as follows:

[0009] S1. Determine the influence of the stress distribution on the cross section of the strip during the weld process. The determination includes: strip shape, F3 roll shape, and bending roll force.

[0010] S2. By analyzing the fluctuation range and amplitude of the F3 rolling force through the weld, the automatic bending force compensation value of the F3 work roll is reasonably determined.

[0011] S3. Automatically adjust the bending force of the F3 work roll based on the actual rolling force variable.

[0012] Preferably, in step S1, the range of rolling force changes caused by the changes in the weld seam and the high-speed steady rolling speed is determined, wherein the rolling speed and F3 rolling force are as follows:

[0013] When the rolling speed range is [100, 250), the change in rolling force ton of F3 is [100, 200);

[0014] When the rolling speed range is [250, 400), the change in rolling force ton of F3 is less than 100.

[0015] Preferably, in step S3, the bending roller force range is 0-30 tons. The bending roller is adjusted according to the plate shape, and the bending roller force is set as follows:

[0016] When the F3 rolling force changes to [0, 100), the F3 bending roll force is automatically compensated to +2 tons.

[0017] When the F3 rolling force changes to [100, 200), the F3 bending roll force is automatically compensated to +4 tons.

[0018] When the change in F3 rolling force (ton) is less than -100, the automatic compensation for F3 bending roll force is -2 tons.

[0019] When the F3 rolling force changes to [-100, 0), the F3 bending roll force is automatically compensated to -4 tons.

[0020] Preferably, the object to which this invention is applicable is a UCMW type four-roll mill.

[0021] (III) Beneficial Effects

[0022] This invention provides a method for improving the stability of the weld zone in a four-stand cold continuous rolling mill. It has the following beneficial effects:

[0023] This method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill involves using an automatic compensation roll bending process for the weld seam rolling of the four-stand rolling mill. This eliminates stress concentration at the edge or center of the strip, improves rolling stability, and reduces the probability of accidents such as cavitation and edge cracking. At the same time, it can calculate the roll bending force compensation model corresponding to the change in the F3 small diameter rolling force in the four-stand rolling mill, and incorporate automatic program control to enhance the degree of mechanization. Attached Figure Description

[0024] Figure 1 This is a graph showing the rolling speed and F3 rolling force data of the present invention;

[0025] Figure 2This is a schematic diagram illustrating the setting of the bending roller force in this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1-2 The present invention provides a technical solution: a method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill, the specific operation of which is as follows:

[0028] It should be noted that the object to which this invention applies is: UCMW type four-stage rolling mill;

[0029] S1. Determine the influence of strip cross-sectional stress distribution during the weld seam transition. This includes determining the strip shape, F3 roll shape, and bending roll force. Also determine the range of rolling force changes caused by variations in weld seam transition and high-speed steady rolling speed. Specifically, the rolling speed and F3 rolling force are as follows:

[0030] When the rolling speed range is [100, 250), the change in rolling force ton of F3 is [100, 200);

[0031] When the rolling speed range (mpm) is [250, 400), the change in rolling force (ton) of F3 is less than 100.

[0032] S2. By analyzing the fluctuation range and amplitude of the F3 rolling force through the weld, the automatic bending force compensation value of the F3 work roll is reasonably determined.

[0033] S3. Automatically adjust the bending force of the F3 work roll based on the actual rolling force variable. The bending force range is 0-30 tons. Adjust the bending force according to the plate shape. The bending force is set as follows:

[0034] When the F3 rolling force changes to [0, 100), the F3 bending roll force is automatically compensated to +2 tons.

[0035] When the F3 rolling force changes to [100, 200), the F3 bending roll force is automatically compensated to +4 tons.

[0036] When the change in F3 rolling force (ton) is less than -100, the automatic compensation for F3 bending roll force is -2 tons.

[0037] When the F3 rolling force changes to [-100, 0), the F3 bending roll force is automatically compensated to -4 tons.

[0038] In summary, this method for improving the stability of the weld seam area in a four-stand cold continuous rolling mill eliminates stress concentration at the edge or center of the strip by employing an automatic compensation bending roll process for the weld seam rolling of the four-stand rolling mill. This improves rolling stability, reduces the probability of cavity opening and edge cracking accidents, and allows for the calculation of the bending roll force compensation model corresponding to the change in the F3 small diameter rolling force in the four-stand rolling mill. By incorporating the program into automatic control, the degree of mechanization is enhanced.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the stability of the weld seam region in a four-stand cold continuous rolling mill, characterized in that: The specific steps are as follows: S1. Determine the influence of the stress distribution on the cross section of the strip during the weld process. The determination includes: strip shape, F3 roll shape of the UCMW type four-roll mill, and bending roll force. In step S1, the range of rolling force changes caused by the changes in the weld seam and the high-speed steady rolling speed is determined, wherein the rolling speed and F3 rolling force are as follows: When the rolling speed range is [100, 250), the change in rolling force ton of F3 is [100, 200); When the rolling speed range (mpm) is [250, 400), the change in rolling force (ton) of F3 is less than 100. S2. By analyzing the fluctuation range and amplitude of the F3 rolling force through the weld, the automatic bending force compensation value of the F3 work roll is reasonably determined. S3. Automatically adjust the bending force of the F3 work roll based on the actual rolling force variable; In step S3, the bending roller force range is 0-30 tons. The bending roller is adjusted according to the plate shape, and the bending roller force is set as follows: When the F3 rolling force changes to [0, 100), the F3 bending roll force is automatically compensated to +2 tons. When the F3 rolling force changes to [100, 200), the F3 bending roll force is automatically compensated to +4 tons. When the change in F3 rolling force (ton) is less than -100, the automatic compensation for F3 bending roll force is -2 tons. When the F3 rolling force changes to [-100, 0), the F3 bending roll force is automatically compensated to -4 tons.

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