Method for calibrating a rolling mill pass

Abstract

This invention provides a method for correcting the pass profile of a continuous rolling mill. The method includes: preparing a correction metal tube; heat-treating the correction metal tube; sequentially passing the correction metal tube through each stand of the continuous rolling mill for rolling; cutting tube segments of length L3 at a second preset distance L2 from the exit of each stand from the correction metal tube as tubes to be inspected; obtaining the center point position and inner hole contour of each tube to be inspected; determining the deviation value of the center position of the pass profile formed by the rollers on the corresponding stand, and determining the deviation value of the pass profile formed by the rollers on the corresponding stand; adjusting the position of the rollers on each stand according to the deviation values ​​of the center position of the pass profile formed by the rollers on each stand and the deviation values ​​of the pass profile formed by the rollers on each stand. The technical solution of this invention can solve the problem of poor correction effect on the rolling center line and pass profile of the continuous rolling mill in existing correction methods.

Description

Technical Field

[0001] This invention relates to the field of seamless steel pipe production technology, and more specifically, to a method for correcting the roll pass of a continuous rolling mill. Background Technology

[0002] In the rolling process of steel pipes, the accuracy of the continuous rolling mill centerline and roll pass alignment are crucial factors determining the wall thickness accuracy and inner hole shape of the steel pipe. Inaccurate roll pass alignment leads to dimensional deviations. During tension reduction, the specific geometry and staggered arrangement of the roll passes cause periodic uneven deformation and accumulation of the wall thickness in the circumferential direction in thick-walled steel pipes with large reduction amounts, ultimately resulting in a hexagonal inner hole. Common tension reduction mills employ a three-roll stand, with the rolls of adjacent stands staggered at a 60° angle. This structure is the fundamental reason for the hexagonal inner hole in thick-walled steel pipes with large reduction amounts.

[0003] Currently, common methods for correcting the rolling centerline and roll pass of continuous rolling mills in the steel pipe industry include laser target measurement and CaliView camera measurement. Laser target measurement utilizes an instrument to emit a visible laser beam. Two points define a straight line, and operators can directly read the offset of each stand's center point relative to this laser reference line using a handheld monitor. Laser emitters and targets are precisely set at both ends of the production line to establish an optical path reference. Dedicated receiving targets are placed sequentially at the center of each stand, and the actual horizontal and vertical deviations are read from the monitor. Based on the deviation data, the stand base or roll position is adjusted in reverse until the reading reaches zero. The deviation value of the rolling centerline (e.g., lateral and vertical deviation) is measured, with a static measurement (no load) accuracy of 0.002 mm. However, the laser target measurement system can only measure the deviation value of the roll pass centerline, not the roll pass profile. It requires an offline workstation to detect stand roll pass assembly errors and stand wear. Furthermore, the laser target measurement method cannot accurately reflect the actual accuracy of the roll pass under loaded conditions during steel pipe rolling. CaliView camera measurement is a mobile online measurement and calibration system for roll pass patterns. During the rolling process of seamless steel pipes, it can quickly detect misalignments in the roll pass patterns. The CaliView camera measurement system mainly consists of three parts: a light source, a high-precision camera, and a portable computer. The system captures the roll pass profile with the camera and compares it with the ideal centerline, measuring the deviation value of the rolling centerline (such as lateral and vertical deviations). The static measurement (no load) accuracy is 0.005 mm, enabling real-time calibration of the roll pass pattern. The measurement results can be immediately displayed and evaluated on the computer. Technicians can adjust the detected deviations on-site and re-measure to confirm the effect. While CaliView camera measurement can achieve high-precision measurements under no-load conditions, it cannot accurately reflect the actual accuracy of the roll pass pattern under loaded conditions during steel pipe rolling. As can be seen from the above, the existing laser target measurement method and CaliView camera measurement method can only correct the rolling center line and die shape of the continuous rolling mill under no-load conditions (i.e., without steel pipe rolling). They cannot accurately reflect the actual accuracy of the die shape under the loaded state during steel pipe rolling, and the correction effect on the rolling center line and die shape of the continuous rolling mill is poor. Summary of the Invention

[0004] The main objective of this invention is to provide a method for correcting the rolling pass of a continuous rolling mill, which can solve the problem that existing correction methods can only correct the rolling center line and pass of the continuous rolling mill under no-load conditions, resulting in poor correction effects.

[0005] To achieve the above objectives, the present invention provides a method for correcting the pass profile of a continuous rolling mill, comprising: preparing a correcting metal tube; heat-treating the correcting metal tube; rolling the correcting metal tube sequentially through each stand of the continuous rolling mill, and stopping rolling when the first end of the correcting metal tube exits the last stand of the continuous rolling mill at a first preset distance L1; cutting tube segments with a length L3 at a second preset distance L2 from the exit of each stand from the correcting metal tube as tubes to be inspected; obtaining the center point position and inner hole profile of each tube to be inspected; comparing the center point position of the tube to be inspected with the theoretical center point position of the pass profile formed by the rollers on the corresponding stand to determine the deviation value of the center position of the pass profile formed by the rollers on the corresponding stand; comparing the inner hole profile of the tube to be inspected with the theoretical profile of the pass profile formed by the rollers on the corresponding stand to determine the profile deviation value of the pass profile formed by the rollers on the corresponding stand; and adjusting the position of the rollers on each stand according to the deviation value of the center position of the pass profile formed by the rollers on each stand and the profile deviation value of the pass profile formed by the rollers on each stand.

[0006] Furthermore, the first preset distance L1 has a range of 2m ≤ L1 ≤ 3m.

[0007] Furthermore, the range of the second preset distance L2 is 0.1m≤L2≤0.15m, and the range of L3 is 0.35m≤L3≤0.45m.

[0008] Furthermore, the heat treatment steps for the calibration metal tube include: preheating the calibration metal tube, wherein the preheating temperature T1 ranges from 130℃ to 200℃ and the preheating time t1 ranges from 2min to 4min; and heating the calibration metal tube, wherein the heating temperature T2 ranges from 260℃ to 280℃ and the heating time t2 ranges from 6min to 8min.

[0009] Furthermore, after the heat treatment step of the straightening metal tube, before the step of rolling the straightening metal tube sequentially through each stand of the continuous rolling mill, the steps include: inserting a mandrel into the straightening metal tube, with both ends of the mandrel extending out of both ends of the straightening metal tube, and the outer wall of the mandrel being in contact with the inner wall surface of the straightening metal tube.

[0010] Further, the step of rolling the correction metal tube sequentially through each stand of the continuous rolling mill and stopping rolling when the first end of the correction metal tube exits the last stand of the continuous rolling mill at a first preset distance L1 includes: rolling the correction metal tube with the mandrel inserted sequentially through each stand of the continuous rolling mill; after the step of rolling the correction metal tube sequentially through each stand of the continuous rolling mill and stopping rolling when the first end of the correction metal tube exits the last stand of the continuous rolling mill at a first preset distance L1, and before the step of cutting the tube segment with a length of L3 at a second preset distance L2 from the exit of each stand from the correction metal tube as the tube to be tested includes: removing the mandrel from the correction metal tube.

[0011] Furthermore, a coordinate measuring machine is used to obtain the center point position and inner hole contour of the tube to be tested.

[0012] Furthermore, the steps for obtaining the center point position of the tube under test using a coordinate measuring machine include: placing the tube under test on the measuring stage of the coordinate measuring machine and fixing it; determining the positions of multiple measuring sections of the tube under test along its axial direction; inserting the probe of the coordinate measuring machine into the inner hole of the tube under test and stopping at the position of the measuring section; then scanning the inner hole of the tube under test along the circumferential direction of the measuring section to obtain the three-dimensional spatial coordinates (X, Y, X) of multiple points on the measuring section. i Y i Z i Repeat the above operation until the three-dimensional spatial coordinates (X, Y, X) of multiple points on all measurement sections are obtained. i Y i Z i ); based on the coordinate point set (X) collected from each measurement section i Y i ), calculate the geometric center coordinates of each measurement section (a i b i ), where j represents the j-th cross section; the coordinates of the geometric centers obtained by fitting all the measured cross sections are weighted and averaged to obtain the center point position of the tube to be tested.

[0013] Furthermore, the steps for measuring the inner hole contour of each tube under test using a coordinate measuring machine include: placing the tube under test on the measuring table of the coordinate measuring machine and fixing it; determining the positions of multiple measurement sections of the tube under test along the axial direction of the tube under test; inserting the probe of the coordinate measuring machine into the inner hole of the tube under test and stopping at the position of the measurement section; then scanning the inner hole of the tube under test along the circumferential direction of the measurement section to obtain the three-dimensional spatial coordinates (Xi, Yi, Zi) of multiple points on the measurement section; and fitting the actual inner hole contour curve of the measurement section based on the three-dimensional coordinate point set (Xi, Yi, Zi) collected from each measurement section.

[0014] Furthermore, the rotational speed N of the rolls in each frame is in the range of 41 rpm ≤ N ≤ 66 rpm; and / or, the correction metal tube is made of aluminum.

[0015] By applying the technical solution of this invention, the correcting metal tube is rolled through multiple stands of a continuous rolling mill. The rolls on the stands apply pressure to the correcting metal tube, which undergoes a plastic deformation process as it passes through the stands. Each tube to be tested retains the true inner hole profile of the corresponding stand at the moment of completion of rolling under loading. By obtaining the center point position and inner hole profile of each tube to be tested, and then comparing the inner hole profile of each tube to be tested with the die profile formed by the rolls on the corresponding stand, and comparing the inner hole profile of the tube to be tested with the theoretical die profile formed by the rolls on the corresponding stand, more accurate deviation values ​​of the rolling center line of the continuous rolling mill and the die profile deviation values ​​of each stand of the continuous rolling mill can be obtained. Finally, based on the deviation values ​​of the center position of the die formed by the rolls on each stand and the die profile deviation values ​​of the rolls on each stand, the correction effect of the rolling center line and die of the continuous rolling mill can be improved.

[0016] Compared with existing technologies (laser target measurement method and CaliView camera measurement method), the continuous rolling mill pass correction method of this application has the following advantages: it overcomes the shortcomings of traditional rolling mill centerline and pass correction technologies, and realizes online measurement of rolling centerline and pass profile under load; it uses aluminum tube as a simulated material and rolls it at a temperature where its yield strength decreases significantly, which is consistent with the actual production of hot-rolled steel tubes; the measurement accuracy of pass profile and center point on the coordinate measuring machine platform reaches 0.002mm; the online measurement of rolling centerline and pass profile of extruded and corrected metal tubes eliminates the dimensional deviation of associated equipment and dies under load, ensuring high dimensional accuracy rolling and inner hole geometry of small-diameter thick-walled tubes. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A flowchart of a continuous rolling mill pass correction method according to an embodiment of the present invention is shown. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, the present invention provides a method for correcting the pass profile of a continuous rolling mill. The method includes: preparing a correction metal tube; heat-treating the correction metal tube; sequentially passing the correction metal tube through each stand of the continuous rolling mill for rolling, stopping rolling when the first end of the correction metal tube exits the last stand of the continuous rolling mill at a first preset distance L1; cutting tube segments with a length L3 at a second preset distance L2 from the exit of each stand from the correction metal tube as tubes to be inspected; obtaining the center point position and inner hole contour of each tube to be inspected; comparing the center point position of the tube to be inspected with the theoretical center point position of the pass profile formed by the rollers on the corresponding stand to determine the deviation value of the center position of the pass profile formed by the rollers on the corresponding stand; comparing the inner hole contour of the tube to be inspected with the theoretical contour of the pass profile formed by the rollers on the corresponding stand to determine the deviation value of the contour of the pass profile formed by the rollers on the corresponding stand; and adjusting the position of the rollers on each stand according to the deviation values ​​of the center position and the contour of the pass profile formed by the rollers on each stand.

[0021] In this embodiment, the melting point of the correction metal tube is less than or equal to 660.37°C, which facilitates heat treatment of the correction metal tube without the need for large heating equipment. The yield strength can be significantly reduced at a lower heating temperature, thereby enabling the true reflection of the geometry and center position of the roll pass under low rolling force.

[0022] The continuous rolling mill consists of six stands, which can be named sequentially as Stand 1, Stand 2, Stand 3, Stand 4, Stand 5, and Stand 6 for easy distinction. Stand 1, Stand 2, Stand 3, Stand 4, Stand 5, and Stand 6 are arranged sequentially along the conveying direction of the straightened metal tube. The diameter of the rolls formed on Stand 1 is larger than that on Stand 2, Stand 2 is larger than that on Stand 3, Stand 3 is larger than that on Stand 4, Stand 4 is larger than that on Stand 5, and Stand 5 is larger than that on Stand 6.

[0023] Passing the corrected metal tube through the stands of the continuous rolling mill in sequence refers to passing the corrected metal tube through the first stand, second stand, third stand, fourth stand, fifth stand, and sixth stand of the continuous rolling mill in sequence.

[0024] The exit of the stand refers to the geometric section position where the rolled tube (e.g., steel tube, aluminum tube, etc.) is most deformed in the roll pass and leaves the contact point of the roll (or leaves the area of ​​the stand).

[0025] The correcting metal tube is heated to facilitate deformation under the pressure of the rollers on the stand. The correcting metal tube is then passed sequentially through each stand of the continuous rolling mill. When the first end of the correcting metal tube (the end that first passes through stand number one) exits the last stand of the continuous rolling mill at a first preset distance L1, each stand has rolled the correcting metal tube. At this point, a tube segment with a length of L3 and a second preset distance L2 from the exit of each stand is cut from the correcting metal tube as the tube to be inspected. A total of six tube segments are cut from the correcting metal tube, resulting in six tubes to be inspected. The pipe segments are designated as follows: Segment 1 (distance L2 from the outlet of rack 1) and L3 (length L3) is designated as Test Pipe 1; Segment 2 (distance L2 from the outlet of rack 2) and L3 (length L3) is designated as Test Pipe 2; Segment 3 (distance L2 from the outlet of rack 3) and L3 (length L3) is designated as Test Pipe 3; Segment 4 (distance L2 from the outlet of rack 4) and L3 (length L3) is designated as Test Pipe 4; Segment 5 (distance L2 from the outlet of rack 5) is designated as Test Pipe 5. The pipe segment with a length of L3 and a second preset distance L2 at the exit of stand 6 is designated as pipe segment 6 to be inspected. Pipe segment 1 to be inspected only passes through the rollers on stand 1, while pipe segment 2 to be inspected only passes through the rollers on both stand 1 and stand 2. Since the diameter of the die formed by the rollers on stand 2 is smaller than that on stand 1, the center point position and inner bore profile of pipe segment 2 can reflect the center point position and profile of the die formed by the rollers on stand 2. Similarly, pipe segment 3 to be inspected only passes through stand 1, stand 2, and stand 3. The rolling process on the rollers of the No. 3 stand is such that the diameter of the die formed by the rollers on the No. 3 stand is smaller than that of the die formed by the rollers on the No. 2 stand. Therefore, the center point position and inner hole contour of the tube to be tested on the No. 3 stand can reflect the center point position and contour of the die formed by the rollers on the No. 3 stand. Similarly, the tube to be tested on the No. 4 stand can reflect the center point position and contour of the die formed by the rollers on the No. 4 stand, the tube to be tested on the No. 5 stand can reflect the center point position and contour of the die formed by the rollers on the No. 5 stand, and the tube to be tested on the No. 6 stand can reflect the center point position and contour of the die formed by the rollers on the No. 6 stand.

[0026] Then, the center point position and inner hole contour of each tube to be tested are obtained. The center point position of each tube to be tested is then compared with the theoretical center point position of the hole formed by the rollers on the corresponding frame to determine the deviation value of the center position of the hole formed by the rollers on the corresponding frame. The inner hole contour of the tube to be tested is then compared with the hole contour of the hole formed by the rollers on the corresponding frame to determine the deviation value of the hole contour of the hole formed by the rollers on the corresponding frame. Finally, the position of the rollers on each frame is adjusted according to the deviation value of the center position of the hole formed by the rollers on each frame and the deviation value of the hole contour of the hole formed by the rollers on each frame.

[0027] This application involves rolling a correcting metal tube through multiple stands of a continuous rolling mill. The rolls on the stands apply pressure to the correcting metal tube, which undergoes a plastic deformation process as it passes through the stands. Each tube to be tested retains the true inner hole profile of the corresponding stand at the moment of completion of rolling under loading. By obtaining the center point position and inner hole profile of each tube to be tested, and then comparing the inner hole profile of each tube to be tested with the die profile formed by the rolls on the corresponding stand, more accurate deviation values ​​of the rolling center line and the die profile deviation values ​​of each stand of the continuous rolling mill can be obtained. Finally, based on the deviation values ​​of the center position of the die formed by the rolls on each stand and the die profile deviation values ​​of the rolls on each stand, the correction effect of the rolling center line and die of the continuous rolling mill can be improved.

[0028] It should be noted that the continuous rolling mill can contain up to 6 stands, which can be increased or decreased according to production needs. Therefore, the above method can also be applied to other numbers of stands, with the number of stands matching the number of tubes to be inspected, and the remaining steps remaining unchanged. The theoretical position of the center point of the die formed by the rollers on the corresponding stand refers to the theoretical position of the center point of the die formed by multiple rollers on the stand when the stand was designed (also known as the center point design position). The center point position of the tube to be inspected reflects the actual position of the center point of the die formed by multiple rollers on the corresponding stand. Similarly, the die profile formed by the rollers on the corresponding stand refers to the theoretical profile of the die formed by multiple rollers on the stand when the stand was designed (also known as the die profile design profile).

[0029] In one embodiment, the step of rolling the straightening metal tube through the stands of a continuous rolling mill includes: translating the straightening metal tube to the entrance of the continuous rolling mill, then manually inserting a mandrel into the straightening metal tube, and releasing the mandrel clamping stand during the rolling process.

[0030] In one embodiment of the present invention, the first preset distance L1 is in the range of 2m≤L1≤3m.

[0031] The above setup ensures that the rollers on each stand roll the correction metal tube, and also prevents the correction metal tube from sagging and deforming due to its own weight due to excessive distance, which would affect the accuracy of subsequent detection of the center point position and inner hole contour of each tube to be tested.

[0032] In one embodiment of the present invention, the value range of the second preset distance L2 is 0.1m≤L2≤0.15m, and the value range of L3 is 0.35m≤L3≤0.45m.

[0033] In this embodiment, the second preset distance L2 is set to 0.1m≤L2≤0.15m, which can ensure that the deformation of the corrected metal tube rolling has been basically stabilized. At the same time, the tube length L3 is set to 0.35m≤L3≤0.45m, which not only ensures sufficient sampling length to eliminate local random errors, but also avoids difficulties in handling and subsequent clamping and positioning due to excessive tube length, and prevents bending deformation caused by the weight of the tube from affecting the measurement accuracy.

[0034] In one embodiment of the present invention, the step of heat treatment of the calibration metal tube includes: preheating the calibration metal tube, wherein the preheating temperature T1 is in the range of 130℃≤T1≤200℃ and the preheating time t1 is in the range of 2min≤t1≤4min; and heating the calibration metal tube, wherein the heating temperature T2 is in the range of 260℃≤T1≤280℃ and the heating time t2 is in the range of 6min≤t2≤8min.

[0035] In this embodiment, the preheating temperature T1 is in the range of 130℃≤T1≤200℃, which ensures that the correction metal tube is heated evenly before high-temperature heating. Then, the heating temperature is controlled at 260℃~280℃ and held for 6~8 minutes, which can significantly reduce the yield strength of the correction metal tube, allowing the correction metal tube to pass through the stand smoothly with extremely low deformation resistance during the subsequent rolling process, thus truly simulating the plastic flow characteristics of high-temperature steel billets during continuous rolling.

[0036] It should be noted that the correction metal tube can be preheated using an offline mandrel preheating furnace, while the correction metal tube can be heated using an online walking beam furnace, in which the correction metal tube enters the walking beam furnace from the continuous rolling back stage and moves back and forth on the roller conveyor inside the furnace.

[0037] In one embodiment of the present invention, after the heat treatment step of the correction metal tube and before the step of rolling the correction metal tube sequentially through each stand of the continuous rolling mill, the method includes: inserting a mandrel into the correction metal tube, with both ends of the mandrel extending out of both ends of the correction metal tube, and the outer wall of the mandrel being in contact with the inner wall surface of the correction metal tube.

[0038] In this embodiment, the mandrel is inserted inside the correction metal tube as an internal support. During the rolling process, it bears the radial pressure of the rollers of the stand and can cooperate with the rollers to roll the correction metal tube, thus realistically simulating the rolling of the steel pipe through the continuous rolling mill. At the same time, the tight fit between the mandrel and the inner wall of the correction metal tube eliminates the relative gap between them, allowing the rolling force to be directly transmitted to the mandrel through the correction metal tube.

[0039] In one embodiment of the present invention, the step of rolling a correction metal tube sequentially through each stand of a continuous rolling mill and stopping rolling when the first end of the correction metal tube exits the last stand of the continuous rolling mill at a first preset distance L1 includes: rolling a correction metal tube with a mandrel inserted sequentially through each stand of the continuous rolling mill; after the step of rolling a correction metal tube sequentially through each stand of the continuous rolling mill and stopping rolling when the first end of the correction metal tube exits the last stand of the continuous rolling mill at a first preset distance L1, and before the step of cutting tube segments with a length of L3 at a second preset distance L2 from the exit of each stand from the correction metal tube as tubes to be tested, the step includes: removing the mandrel from the correction metal tube.

[0040] In this embodiment, the corrected metal tubes, each equipped with a mandrel, are sequentially rolled through the stands of a continuous rolling mill, allowing the rollers and mandrels of the stands to work together to roll the corrected metal tubes. Before the step of cutting the tubes to be tested from the corrected metal tubes, the mandrels are removed from the corrected metal tubes to facilitate subsequent cutting of tube segments.

[0041] It should be noted that a rod removal machine can be used to remove the mandrel from the calibration metal tube.

[0042] In one embodiment of the present invention, a coordinate measuring machine is used to measure the center point position and inner hole contour of each tube to be tested.

[0043] In this embodiment, the coordinate measuring machine has high-precision positioning and detection capabilities at the micrometer level (0.002mm). It can obtain the center point position and inner hole contour of the tube to be tested by multi-point contact of the probe. Compared with traditional laser or vision measurement, this contact precision measurement directly acts on the deformed physical entity and can truly reflect the actual geometric state of the roll pass under loading, providing reliable and quantitative data support for the fine adjustment of the continuous rolling mill stand.

[0044] In one embodiment of the present invention, the step of obtaining the center point position of the tube to be inspected using a coordinate measuring machine includes: placing the tube to be inspected on the measuring stage of the coordinate measuring machine and fixing the tube; determining the positions of multiple measuring sections of the tube to be inspected along the axial direction of the tube; inserting the probe of the coordinate measuring machine into the inner hole of the tube to be inspected and stopping at the position of the measuring section; and then scanning the inner hole of the tube to be inspected along the circumferential direction of the measuring section to obtain the three-dimensional spatial coordinates (X, Y, X) of multiple points on the measuring section. i Y i Z i Repeat the above operation until the three-dimensional spatial coordinates (X, Y, X) of multiple points on all measurement sections are obtained. i Y i Z i ); based on the coordinate point set (X) collected from each measurement section i Y i ), calculate the geometric center coordinates of each measurement section (a i b i ), where j represents the j-th cross section; the coordinates of the geometric centers obtained by fitting all the measured cross sections are weighted and averaged to obtain the center point position of the tube to be tested.

[0045] In this embodiment, the above steps can accurately quantify the comprehensive deviation value of the rolling centerline in the horizontal and vertical directions. This deviation value not only reflects the adjustment error of the mechanical position of the stand, but also provides comprehensive and accurate data for the fine correction of the continuous rolling mill, which is significantly better than the traditional method that can only measure the static position.

[0046] It should be noted that the steps of comparing the center point of the tube to be tested with the theoretical center point of the die formed by the rollers on the corresponding stand, and comparing the inner hole contour of each tube to be tested with the die contour of the rollers on the corresponding stand, can be accomplished by first inputting the coordinates and contours of the center positions of the dies formed by multiple rollers on each stand of the continuous rolling mill into a coordinate measuring machine. This allows for obtaining the deviation values ​​of the center positions of the dies formed by the rollers on the stand and the deviation values ​​of the die contours. There are generally three rollers on each stand, and these three rollers form the die.

[0047] In one embodiment of the present invention, the step of measuring the inner hole contour of each tube to be tested using a coordinate measuring machine includes: placing the tube to be tested on the measuring stage of the coordinate measuring machine and fixing the tube; determining the positions of multiple measuring sections of the tube to be tested along the axial direction of the tube; inserting the probe of the coordinate measuring machine into the inner hole of the tube to be tested and stopping at the position of the measuring section, and then scanning the inner hole of the tube to be tested along the circumferential direction of the measuring section to obtain the three-dimensional spatial coordinates (Xi, Yi, Zi) of multiple points on the measuring section; and fitting the actual inner hole contour curve of the measuring section based on the set of three-dimensional coordinate points (Xi, Yi, Zi) collected from each measuring section.

[0048] In this embodiment, the above steps can comprehensively and meticulously reconstruct the complete geometric shape of the inner hole of the tube to be tested, overcoming the limitations of traditional methods that only measure the diameter or center point and cannot reflect complex shape errors. This provides a refined basis for optimizing the roll pass design of the continuous rolling mill, adjusting the roll gap and eccentricity, and ensuring that the inner hole shape of the final produced steel tube meets high precision requirements.

[0049] In one embodiment of the present invention, the rotational speed N of the rolls of each stand is in the range of 41 rpm ≤ N ≤ 66 rpm.

[0050] In this embodiment, the rotational speed N of the rolls in each stand is in the range of 41rpm≤N≤66rpm, to ensure that the tube to be tested has enough time to complete plastic deformation and stabilize under force when passing through the stand, and to avoid interference with measurement accuracy due to dynamic inertial force, vibration or thermal effect generated by high-speed rolling.

[0051] In one embodiment of the present invention, the correction metal tube is made of aluminum.

[0052] In this embodiment, aluminum is chosen as the calibration metal tube material because the yield strength of pure aluminum decreases significantly at 260℃~280℃. Its plastic flow characteristics can well simulate the deformation behavior of high-temperature steel billets during continuous rolling. In addition, aluminum has good ductility and low deformation resistance, which can not only accurately reflect the geometry and center position of the roll pass under low rolling force, but also avoid the risk of roll damage or mandrel jamming caused by excessively hard material. Thus, while ensuring measurement safety, high-fidelity reproduction of the roll pass accuracy under the loading state of the continuous rolling mill can be achieved.

[0053] In one embodiment, the rollers of each frame are driven to rotate by a motor, and the specific motor speed can be found in Table 1.

[0054] Table 1 Motor Speed

[0055]

[0056] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: by rolling the correcting metal tube through multiple stands of a continuous rolling mill, the rolls on the stands apply pressure to the correcting metal tube, and the correcting metal tube undergoes a plastic deformation process when passing through the stands. Each tube to be tested retains the true inner hole contour of the corresponding stand at the moment of completion of rolling under the loading state. By obtaining the center point position and inner hole contour of each tube to be tested, and then comparing the inner hole contour of each tube to be tested with the die contour formed by the rolls on the corresponding stand, and comparing the inner hole contour of the tube to be tested with the theoretical die contour formed by the rolls on the corresponding stand, more accurate deviation values ​​of the rolling center line of the continuous rolling mill and the die contour deviation values ​​of each stand of the continuous rolling mill can be obtained. Finally, based on the deviation values ​​of the center position of the die formed by the rolls on each stand and the die contour deviation values ​​of the rolls on each stand, the correction effect of the rolling center line and die of the continuous rolling mill can be improved.

[0057] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0058] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for correcting the roll pass of a continuous rolling mill, characterized in that, include: Material preparation and alignment of metal pipes; The corrective metal tube is subjected to heat treatment; The corrected metal tube is rolled sequentially through each stand of the continuous rolling mill, and rolling is stopped when the first end of the corrected metal tube exits the last stand of the continuous rolling mill by a first preset distance L1. A pipe segment with a length of L3 and a second preset distance L2 from the outlet of each of the aforementioned racks is cut off from the calibration metal pipe and used as the pipe to be tested. Obtain the center point position and inner hole contour of each of the tubes to be tested; The center point position of the tube to be tested is compared with the theoretical center point position of the hole formed by the roller on the frame to determine the deviation value of the center position of the hole formed by the roller on the frame. The inner hole contour of the tube to be tested is compared with the theoretical contour of the hole formed by the roller on the frame to determine the contour deviation value of the hole formed by the roller on the frame. The positions of the rollers on each frame are adjusted based on the deviation values ​​of the center positions of the holes formed by the rollers on each frame and the deviation values ​​of the hole profiles formed by the rollers on each frame.

2. The continuous rolling mill pass correction method according to claim 1, characterized in that, The first preset distance L1 has a value range of 2m≤L1≤3m.

3. The continuous rolling mill pass correction method according to claim 1, characterized in that, The second preset distance L2 has a value range of 0.1m≤L2≤0.15m, and the value range of L3 has a value range of 0.35m≤L3≤0.45m.

4. The continuous rolling mill pass correction method according to any one of claims 1 to 3, characterized in that, The steps for heat-treating the corrected metal tube include: The correction metal tube is preheated, and the preheating temperature T1 is in the range of 130℃≤T1≤200℃, and the preheating time t1 is in the range of 2min≤t1≤4min. The correction metal tube is heated, with the heating temperature T2 ranging from 260℃ to T1 to 280℃ and the heating time t2 ranging from 6min to t2 to 8min.

5. The continuous rolling mill pass correction method according to any one of claims 1 to 3, characterized in that, The step of heat-treating the straightened metal tube and the step of rolling the straightened metal tube sequentially through each stand of a continuous rolling mill include: The mandrel is inserted into the calibration metal tube, with both ends of the mandrel extending beyond the ends of the calibration metal tube, and the outer wall of the mandrel fitting against the inner wall of the calibration metal tube.

6. The continuous rolling mill pass correction method according to claim 5, characterized in that, The step of rolling the corrected metal tube sequentially through each stand of the continuous rolling mill and stopping the rolling when the first end of the corrected metal tube leaves the exit of the last stand of the continuous rolling mill by a first preset distance L1 includes: rolling the corrected metal tube with the mandrel inserted through it sequentially through each stand of the continuous rolling mill. After the step of rolling the corrected metal tube sequentially through each stand of the continuous rolling mill, and stopping rolling when the first end of the corrected metal tube exits the last stand of the continuous rolling mill at a first preset distance L1, the step of cutting tube segments with a length of L3 and a distance of a second preset distance L2 from the exit of each stand from the corrected metal tube as tubes to be tested includes: The mandrel is dislodged from the calibration metal tube.

7. The method for correcting the pass shape of a continuous rolling mill according to any one of claims 1 to 3, characterized in that, The center point position and inner hole contour of the tube to be tested are obtained using a coordinate measuring machine.

8. The continuous rolling mill pass correction method according to claim 7, characterized in that, The steps for obtaining the center point position of the tube to be inspected using a coordinate measuring machine include: The tube to be tested is placed on the measuring platform of the coordinate measuring machine and the tube to be tested is fixed. The positions of multiple measurement sections of the tube to be tested are determined along the axial direction of the tube to be tested; The probe of the coordinate measuring machine (CMM) is inserted into the inner hole of the tube to be inspected and stopped at the position of the measurement section. Then, the probe of the CMM scans the inner hole of the tube to be inspected along the circumferential direction of the measurement section to obtain the three-dimensional spatial coordinates (X, Y, X) of multiple points on the measurement section. i Y i Z i Repeat the above operation until the three-dimensional spatial coordinates (X, Y, X) of all points on the measurement section are obtained. i Y i Z i ); Based on the coordinate point set (X) collected from each of the aforementioned measurement sections i Y i ), calculate the geometric center coordinates (a) of each of the measured sections. i b i ), where j represents the j-th section; The center point of the tube to be tested is obtained by taking a weighted average of the coordinates of the geometric centers obtained by fitting all the measured cross sections.

9. The continuous rolling mill pass correction method according to claim 7, characterized in that, The steps for measuring the inner diameter profile of the tube under test using a coordinate measuring machine include: The tube to be tested is placed on the measuring platform of the coordinate measuring machine and the tube to be tested is fixed. The positions of multiple measurement sections of the tube to be tested are determined along the axial direction of the tube to be tested; The probe of the coordinate measuring machine is inserted into the inner hole of the tube to be tested and stopped at the position of the measurement section. Then, the probe of the coordinate measuring machine scans the inner hole of the tube to be tested along the circumferential direction of the measurement section to obtain the three-dimensional spatial coordinates (Xi, Yi, Zi) of multiple points on the measurement section. Based on the three-dimensional coordinate point set (Xi, Yi, Zi) collected from each of the measurement sections, the actual contour curve of the inner hole of the measurement section is fitted.

10. The continuous rolling mill pass correction method according to any one of claims 1 to 3, characterized in that, The rotational speed N of the rolls in each of the aforementioned frames is in the range of 41 rpm ≤ N ≤ 66 rpm; and / or, the correction metal tube is made of aluminum.

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