Roll gap calibration and operation method of a hot straightening machine

Abstract

This invention discloses a roller gap calibration method for a hot straightening machine, belonging to the field of high-temperature metallurgical technology. The method involves adjusting the inlet and outlet rollers to be lower than several intermediate working rollers, placing the calibration plate between the intermediate working rollers and the upper working roller, and adjusting the height of the upper working roller using a hydraulic cylinder adjustment assembly until it contacts the upper surface of the calibration plate. This ensures that the thickness of the current intermediate working rollers and the upper working rollers matches the thickness of the calibration plate. A height adjustment device is used to adjust the inlet roller to contact the calibration plate, and the height adjustment device is also used to adjust the outlet roller to contact the calibration plate. This method avoids the phenomenon of manual adjustment affecting calibration time when the roller box diameter is different. Calibration can be completed quickly regardless of the roller box diameter, ensuring successful calibration after roller box replacement, reducing manual adjustment time, and improving calibration efficiency.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature metallurgical technology, specifically a roller gap calibration method for a hot straightening machine. Background Technology

[0002] A hot straightener is an important piece of equipment used for straightening steel. It shapes and corrects materials through the squeezing and straightening force between upper and lower rollers. During the straightening process, the width of the roller gap directly determines the straightening accuracy; therefore, the roller gap needs to be calibrated to ensure it matches the set process parameters during actual operation. The calibration process mainly involves setting a calibration plate of standard thickness, adjusting the roller gap between the upper and lower rollers of the straightener to match the calibration plate, and calibrating the height of the inlet and outlet rollers and the point of application of the straightening force. Accurate roller gap calibration is a crucial prerequisite for ensuring the normal operation of the straightener, improving straightening quality, and avoiding material processing defects.

[0003] However, the calibration process of existing hot straightening machines still has many drawbacks. Traditional calibration methods usually require manual intervention, adjusting the roll gap by manually adjusting the position of the upper or lower roller box. However, this method is complex, inefficient, and easily affected by human error. Existing calibration methods lack automation capabilities, and repeated calibration is required after frequent roller changes, further reducing production efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a roller gap calibration method for a hot straightening machine and its operation method, so as to solve the problem that the existing calibration methods lack automation adaptability and require repeated calibration after frequent roller changes, which further reduces production efficiency.

[0005] The first aspect of this invention provides a roll gap calibration method for a hot straightening machine, characterized by comprising the following steps:

[0006] S1. Adjust the inlet roller and outlet roller to be lower than several intermediate working rollers, and send the calibration plate between several intermediate working rollers and the upper working roller;

[0007] S2. Adjust the height of the upper working roller through the hydraulic cylinder adjustment assembly until it contacts the upper surface of the calibration plate, so that the thickness of the current middle working roller and the upper working roller is the thickness of the calibration plate.

[0008] S3. Adjust the inlet roller to contact the calibration plate using the height adjustment device, and adjust the outlet roller to contact the calibration plate using the height adjustment device;

[0009] S4. Adjust the upper working roll again using the hydraulic cylinder adjustment assembly until the height of the upper working roll, the middle working roll, the inlet roll, and the outlet roll reaches the position of the heat straightening roll gap.

[0010] As a further aspect of the present invention: in step S1, the height of the inlet roller and the outlet roller is 4-8 mm lower than the height of several intermediate working rollers, specifically 5 mm in this embodiment. By calculating the stroke of the height adjustment component, the starting height is dynamically adjusted to adapt to different equipment states and roller diameters, ensuring that the calibration force is determined by the contact force between the intermediate working roller and the upper working roller, thereby improving calibration accuracy and avoiding abnormal straightening force.

[0011] As a further aspect of the present invention: In step S2, the hydraulic cylinder adjustment assembly includes four straightening hydraulic cylinders, each of the four straightening hydraulic cylinders having an upper roller box fixedly connected to its telescopic end. Several intermediate working rollers are arranged below the upper roller box. Each of the four straightening hydraulic cylinders is equipped with a first pressure sensor and a first displacement sensor. The pressure sensor is used to detect the oil pressure on the piston side and rod side of the hydraulic cylinder. The force exerted by the straightening hydraulic cylinder on the upper roller box is calculated using the physical formula F=PS, thereby obtaining the straightening force exerted by the several upper working rollers below this position on the steel plate. The pressure sensor is installed on the piston side cylinder wall of the upper roller box and on the valve platform controlling the oil on the piston side and rod side of the hydraulic cylinder.

[0012] The displacement sensor is used to detect the length of the cylinder rod extension. The straightening cylinder is installed upside down (piston side up, rod side down). When the rod extends (the displacement sensor detects the extension amount), the upper roller box moves downward, and the change in the straightening roller gap is obtained by the change in the displacement sensor.

[0013] As a further aspect of the present invention: in step S2, the four correction cylinders descend rapidly at a speed of 9~10 mm / s until they reach the deceleration position, and then the four correction cylinders descend slowly at a speed of 0.10~0.20 mm / s until the upper working roller contacts the upper surface of the calibration plate and enters the force control mode.

[0014] As a further aspect of the present invention: In step S2, under force control mode, the four straightening cylinders are adjusted so that the straightening force detected by them reaches 500kN, so that the thickness of the current intermediate working roller and the upper working roller is the thickness of the calibration plate.

[0015] As a further aspect of the present invention: in step S2, the thickness of the calibration plate is 99mm. By adjusting the correction cylinder, the roll gap thickness is made equal to the thickness of the calibration plate (99mm). The uniform thickness standard avoids roll gap calibration errors caused by differences in the thickness of the calibration plate.

[0016] As a further aspect of the present invention: In step S3, the height adjustment device includes two adjusting cylinders, which are respectively positioned below the inlet roller and the outlet roller. Each adjusting cylinder has a first wedge at its telescopic end. A second wedge is slidably connected above the first wedge, which is positioned below the lower roller box. The lower roller box contains the inlet roller, the outlet roller, and several intermediate working rollers. The two adjusting cylinders are located below the inlet roller and the outlet roller, respectively, and are used to independently adjust the height of the inlet roller and the outlet roller. The adjusting cylinders are positioned at their telescopic ends and move up and down with the cylinder's movement. The second wedge is slidably connected above the first wedge and can slide along the inclined surface of the first wedge to achieve fine-tuning of the height. This ensures that the height of the adjusting cylinder matches the calibration plate, achieving contact with the calibration plate. During calibration, the height of the adjusting cylinder is ensured to be lower than the intermediate working rollers to avoid affecting the force distribution on the calibration plate.

[0017] As a further aspect of the present invention: In step S3, the adjusting cylinder below the inlet roller is extended and retracted to gradually raise the inlet roller until it contacts the calibration plate, so that the height difference between the current inlet roller and the intermediate working roller is 0, and the gap between the inlet roller and the intermediate working roller is equal to the thickness of the calibration plate (99mm). As the inlet roller gradually approaches the calibration plate, the system monitors the change in contact force in real time. When the contact force reaches a preset value and causes a change in the gap of 0.1mm, the adjustment is stopped, and the calibration is completed.

[0018] As a further aspect of the present invention: In step S3, the adjusting cylinder below the exit roller extends and retracts, causing the exit roller to gradually rise and contact the calibration plate, making the height difference between the current exit roller and the intermediate working roller zero, indicating that they are on the same horizontal plane. The extension and retraction movement drives the first wedge block to move forward or backward, adjusting the height of the exit roller. The first wedge block moves forward under the drive of the adjusting cylinder, pushing the second wedge block to slide through its inclined surface, indirectly raising or lowering the height of the exit roller. As the exit roller gradually approaches the calibration plate, the system monitors the change in contact force in real time. When the contact force reaches a preset value and causes a change of 0.1 mm in the roller gap, the adjustment stops, and the calibration is completed.

[0019] As a further aspect of the present invention: In step S4, the height of the upper working roller is adjusted using a hydraulic cylinder adjustment assembly until the height difference between the upper working roller and the intermediate working roller, inlet roller, and outlet roller is 140mm. The lifting and lowering of the upper working roller is controlled by the hydraulic cylinder adjustment assembly to ensure that its height is adjusted to the target position of 140mm. The upper working roller is adjusted by 41mm based on the calibration plate thickness to ensure that the adjustment accuracy meets production requirements. The height of the upper working roller is adjusted to the additional 41mm based on the calibration plate thickness using the hydraulic cylinder adjustment assembly, ensuring that the roll gap of the hot straightener meets the standard height difference of 140mm required for production operation. After adjustment, the height of each working roller is consistent, ensuring stable roll gap operation and avoiding equipment problems or process deviations caused by height differences. The automatic adjustment process reduces manual intervention, improves calibration efficiency, simplifies the operation process, and protects the integrity of the equipment and calibration plate.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] After the heat straightening calibration begins, the relevant devices reach the starting position. The starting position of the inlet and outlet rollers is no longer determined by lowering a fixed height from the current zero position, but by fully retracting the height adjustment cylinder to ensure that the height of the inlet and outlet rollers is lower than that of the intermediate working roller. This ensures that no force is exerted on the calibration plate during the roller gap calibration process, thereby ensuring the accuracy of the roller gap and the accuracy of the zero position of the inlet and outlet roller heights.

[0022] In addition, the hydraulic cylinder adjustment assembly adjusts the height of the upper working roller. During the rapid movement from the initial position to the deceleration position, until it contacts the upper surface of the calibration plate, the initial position is quickly adjusted to avoid excessive impact force caused by changes in roller box height. After detecting contact force, it gradually switches to force control mode to avoid excessive force during simultaneous switching. The heights of the inlet and outlet rollers are adjusted to gradually contact the calibration plate, ensuring stability during the calibration process. This avoids the phenomenon of manual adjustment affecting calibration time when roller box diameters are different. Calibration can be completed quickly regardless of roller box diameter, ensuring successful calibration after roller box replacement. This reduces manual adjustment time and improves calibration efficiency. Attached Figure Description

[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a front view schematic diagram of the roll gap calibration and operation method of a thermal straightening machine;

[0025] Figure 2 This is a schematic diagram of the overall side view structure provided by the present invention;

[0026] Figure 3The present invention provides a flowchart of the roller gap calibration and operation method of a hot straightening machine.

[0027] The markings in the diagram are: 1. Upper roller box; 11. Upper work roller; 2. Lower roller box; 21. Lower work roller assembly; 211. Inlet roller; 212. Intermediate work roller; 213. Outlet roller; 3. Hydraulic cylinder adjustment assembly; 31. Correction cylinder; 4. Height adjustment device; 41. First wedge; 42. Second wedge; 43. Adjustment cylinder; 5. Calibration plate. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Please see Figure 1-3 As shown in the embodiment of the present invention, a roller gap calibration method for a hot straightening machine includes the following steps:

[0031] S1. Adjust the inlet roller 211 and outlet roller 213 to be lower than several intermediate working rollers 212, and send the calibration plate 5 between several intermediate working rollers 212 and the upper working roller 11.

[0032] In this step, the calibration plate 5 is placed between the intermediate working roller 212 and the upper working roller 11 to ensure that the inlet roller 211 and the outlet roller 213 do not apply force to the calibration plate 5, so as to reduce interference during the calibration process.

[0033] S2. Adjust the height of the upper working roller 11 by the hydraulic cylinder adjustment assembly 3 until it contacts the upper surface of the calibration plate 5, so that the thickness of the current intermediate working roller 212 and the upper working roller 11 is the thickness of the calibration plate 5.

[0034] In this step, the height of the upper working roller 11 is adjusted using the hydraulic cylinder adjustment component 3. During the process of the hydraulic cylinder adjustment component 3 moving quickly from the initial position to the deceleration position until it contacts the upper surface of the calibration plate 5, the initial position is quickly adjusted to avoid excessive impact force caused by the change in roller box height. After the contact force is detected, it gradually switches to the force control mode to avoid generating excessive force when switching at the same time.

[0035] S3. Adjust the inlet roller 211 to contact the calibration plate 5 by adjusting the height adjustment device 4, and adjust the outlet roller 213 to contact the calibration plate 5 by adjusting the height adjustment device 4.

[0036] In this step, the heights of the inlet roller 211 and the outlet roller 213 are adjusted so that they gradually contact the calibration plate 5, ensuring the smoothness of the calibration process.

[0037] S4. Adjust the upper working roller 11 again using the hydraulic cylinder adjustment assembly 3 until the height of the upper working roller 11, the intermediate working roller 212, the inlet roller 211, and the outlet roller 213 reaches the position of the heat straightening roller gap, thus achieving roller gap adjustment and completing calibration. The above steps achieve fully automatic calibration, avoiding manual adjustment, improving efficiency and success rate. It avoids the phenomenon of manual adjustment affecting calibration time when the roller box diameter is different. Calibration can be completed quickly regardless of the roller box diameter, ensuring successful calibration after roller box replacement. This reduces manual adjustment time and improves calibration efficiency.

[0038] Furthermore, in step S2, the height of the inlet roller 211 and the outlet roller 213 is 4-8 mm lower than the height of several intermediate working rollers 212, specifically 5 mm in this embodiment. The height of the inlet roller 211 and the outlet roller 213 must be precisely lower than all intermediate working rollers 212 to avoid them interfering with the calibration force. The starting height is dynamically adjusted by calculating the stroke of the height adjustment device 4 to adapt to different equipment states and roller diameters, ensuring that the calibration force is determined by the contact force between the intermediate working rollers 212 and the upper working roller 11, thereby improving the calibration accuracy and avoiding abnormal straightening force.

[0039] Furthermore, in step S2, the cylinder adjustment assembly 3 includes four straightening cylinders 31. The telescopic ends of the four straightening cylinders 31 are fixedly connected to the four corners of the upper roller box 1. Pressure sensors and displacement sensors are installed on the four straightening cylinders 31. The pressure sensors (used to detect the oil pressure on the piston side and rod side of the cylinder, and calculate the force of the straightening cylinder 31 acting on the upper roller box 1 using the physical formula: F=PS, thereby obtaining the straightening force of several upper working rollers 11 below this position acting on the steel plate, the specific model of the pressure sensor is (HDA3840A-350-Y24) installed on the piston side cylinder wall of the upper roller box 1 and on the valve platform controlling the oil on the piston side and rod side of the cylinder)

[0040] The displacement sensor is used to detect the length of the cylinder rod extension. The specific model is (MTS, RHS0260MD701S1G6100). It is installed on the piston side of the cylinder. The straightening cylinder 31 is installed upside down (piston side up, rod side down). When the rod extends (the displacement sensor detects the rod extension), the upper roller box 1 moves downward, and the change in the straightening roller gap is obtained by the change in the displacement sensor.

[0041] Furthermore, in step S2, the four correction cylinders 31 descend rapidly at a speed of 9~10 mm / s, specifically 9.5 mm / s in this embodiment, until they reach the deceleration position. Then, the four correction cylinders 31 descend slowly at a speed of 0.10~0.20 mm / s, specifically 0.15 mm / s in this embodiment, until the upper working roller 11 contacts the upper surface of the calibration plate 5, entering the force control mode. The rapid descent phase is used to quickly move the upper working roller 11 to a position close to the calibration plate 5. Through high-speed operation, the ineffective stroke time is greatly reduced, and the calibration efficiency is improved.

[0042] When the roller gap reaches 110mm (at which point the distance between the upper working roller 11 and several intermediate working rollers 212 is 110mm and the roller gap is at this distance), a slow descent phase begins, with a speed of 0.15mm / s. This ensures that the upper working roller 11 smoothly contacts the calibration plate 5. During the slow descent and contact process, the contact force is gradually detected and switched to force control to ensure the stability of the force value during the calibration process. When the contact force is detected, the straightening cylinder 31 switches from position control mode to force control mode, gradually adjusting the contact force to the calibration force. This avoids excessive impact force that might occur if the rollers directly contact the calibration plate 5 after a rapid descent, and prevents some positions from prematurely pressing against the calibration plate 5 during positioning by the upper roller box 1, which could cause excessive straightening impact force and damage to some support roller bearings.

[0043] Further, in step S2, in force control mode, the four straightening cylinders 31 are adjusted to detect a straightening force of 500kN, so that the thickness of the current intermediate working roller 212 and the upper working roller 11 is the thickness of the calibration plate 5; at this time, the four straightening cylinders 31 move synchronously at the same speed and position. The straightening cylinder 31 that first detects the contact force switches to force control mode and maintains the contact force, while the remaining straightening cylinders 31 continue position control, gradually detecting the contact force and switching to force control mode. After all the straightening cylinders 31 enter force control mode, the straightening force is uniformly adjusted to 500kN to ensure that the thickness of the intermediate working roller 212 and the upper working roller 11 is equal to the thickness of the calibration plate 5. In position control mode, the four straightening cylinders 31 move at the same speed and position. Once a straightening cylinder 31 detects the contact force, it immediately switches from position control mode to force control mode and maintains the contact force, while the other straightening cylinders 31 continue to move in position control mode until they detect the contact force one by one and switch to force control mode. The independent switching mode allows the straightening cylinder 31 to gradually switch to force control, avoiding the situation where other straightening cylinders 31 have not yet detected contact force when the force value of one straightening cylinder 31 is too large (close to or exceeding 1500kN). This reduces manual intervention and adjustment of position offset values, making the calibration process more automated. In force control mode, the straightening cylinder 31 is synchronously adjusted to the target straightening force (500kN), ensuring the accuracy and consistency of the calibrated thickness.

[0044] Furthermore, in step S2, the thickness of calibration plate 5 is 99mm. Calibration plate 5 is placed between the intermediate working roller 212 and the upper working roller 11. By adjusting the correction cylinder 31, the roller gap thickness is made equal to the thickness of calibration plate 5 (99mm). The uniform thickness standard avoids roller gap calibration errors caused by the difference in the thickness of calibration plate 5.

[0045] In one embodiment, in step S3, the height adjustment device 4 includes two adjusting cylinders 43, which are respectively located below the inlet roller 211 and the outlet roller 213. Each adjusting cylinder 43 has a first wedge 41 at its telescopic end, and a second wedge 42 is slidably connected above the first wedge 41. The second wedge 42 is located below the lower roller box 2. The lower roller box 2 is equipped with the inlet roller 211, the outlet roller 213, and several intermediate working rollers 212. The two adjusting cylinders 43 are located below the inlet roller 211 and the outlet roller 213, respectively, and are used to independently adjust the height of the inlet roller 211 and the outlet roller 213. Located at the telescopic end of the adjusting cylinder 43, the first wedge 41 is adjusted to move, and the second wedge 42 is slidably connected above the first wedge 41, allowing it to slide along the inclined surface of the first wedge 41 to achieve fine-tuning of the height, ensuring that the height of the adjusting cylinder 43 matches the calibration plate 5 and achieves contact with the calibration plate 5. During the calibration process, ensure that the height of the adjusting cylinder 43 is lower than that of the intermediate working roller 212 to avoid affecting the force distribution on the calibration plate 5.

[0046] Further, in step S3, by controlling the extension and retraction of the adjusting cylinder 43, the inlet roller 211 is gradually raised to contact the calibration plate 5, so that the height difference between the current inlet roller 211 and the intermediate working roller 212 is 0. The adjusting cylinder 43, through its extension and retraction action, drives the inlet roller 211 to rise via the second wedge block 42, gradually contacting the calibration plate 5. The height difference between the inlet roller 211 and the intermediate working roller 212 is 0, indicating that they are on the same horizontal plane. The roller gap between the inlet roller 211 and the intermediate working roller 212 is equal to the thickness of the calibration plate 5 (99mm). As the inlet roller 211 gradually approaches the calibration plate 5, the system monitors the change in contact force in real time. When the contact force reaches the preset value and causes a change of 0.1mm in the roller gap, the adjustment stops, and the calibration is completed.

[0047] In one embodiment, in step S3, the adjusting cylinder 43 below the exit roller 213 extends and retracts, causing the exit roller 213 to gradually rise and contact the calibration plate 5, making the height difference between the current exit roller 213 and the intermediate working roller 212 zero. The adjusting cylinder 43 is located below the exit roller 213, and its extension and retraction movement drives the first wedge block 41 to move forward or backward, adjusting the height of the exit roller 213. The first wedge block 41 moves forward under the drive of the adjusting cylinder 43, and pushes the second wedge block 42 to slide through its inclined surface, indirectly raising or lowering the height of the exit roller 213. As the exit roller 213 gradually approaches the calibration plate 5, the system monitors the change in contact force in real time. When the contact force reaches a preset value and causes a change of 0.1 mm in the roller gap, the adjustment stops, and the calibration is completed.

[0048] In one embodiment, in step S4, the height difference between the upper working roll 11 and the intermediate working roll 212, the inlet roll 211, and the outlet roll 213 is 140mm. The lifting and lowering of the upper working roll 11 is adjusted by the hydraulic cylinder adjustment assembly 3 to ensure that its height is adjusted to the target position of 140mm. The upper working roll 11 is adjusted by 41mm based on the thickness of the calibration plate 5 to ensure that the adjustment accuracy meets the production requirements. The height of the upper working roll 11 is adjusted to the additional 41mm based on the thickness of the calibration plate 5 by the hydraulic cylinder adjustment assembly 3 to ensure that the roll gap of the hot straightener reaches the standard height of 140mm required for production operation. After adjustment, the height of each working roll is consistent, ensuring stable roll gap operation and avoiding equipment problems or process deviations caused by height differences. The automatic adjustment process reduces manual intervention, improves calibration efficiency, simplifies the operation process, and protects the integrity of the equipment and the calibration plate 5.

[0049] After the roller box is replaced or the roller diameter changes, the straightening cylinder 31 automatically cancels the rapid movement from the initial position to the deceleration position. It directly starts from the starting position, clears the straightening force to zero, and begins to decelerate towards the calibration plate 5 to detect the contact force. This avoids the excessive straightening impact force generated by the rapid movement during position control due to the change in the height of the upper roller box 1, which could damage the support roller bearings of the roller box. This avoids the situation where, regardless of the roller box diameter, the rapid movement of the upper roller box 1 during positioning causes some positions to press against the calibration plate 5 prematurely, resulting in excessive straightening impact force and damage to some support roller bearings.

[0050] The process of switching the movement of the straightening cylinder 31 from position control to force control mode involves one straightening cylinder 31 detecting contact force, then switching to force control and maintaining that contact force. This continues until the other hydraulic cylinders gradually detect contact force and switch to force control mode accordingly. In other words, during the switch from position to force control, all four straightening cylinders 31 are controlled independently and maintained at the contact force. Once all four cylinders have switched to force control, the force is adjusted synchronously to the calibration force. This avoids excessive force in some straightening cylinders 31 during simultaneous switching, which could lead to calibration failure. It also avoids the large deviation in straightening force that would occur before and after roller box replacement when all cylinders switch to force control simultaneously, requiring multiple manual interventions to ensure calibration success.

[0051] It can avoid the phenomenon of excessive straightening force damaging the support roller bearings and the phenomenon of manual calibration affecting the calibration time when the roller box diameter is different. This ensures that the calibration process is fully automatic except for the confirmation of calibration plate 5, and achieves successful calibration of the straightener roller gap in one go after the roller box is replaced.

[0052] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for calibrating the roll gap of a hot straightening machine and its operation, characterized in that, Includes the following steps: S1. Adjust the inlet roller and outlet roller to be lower than several intermediate working rollers, and send the calibration plate between several intermediate working rollers and the upper working roller; S2. Adjust the height of the upper working roller through the hydraulic cylinder adjustment assembly until it contacts the upper surface of the calibration plate, so that the thickness of the current middle working roller and the upper working roller is the thickness of the calibration plate. S3. Adjust the inlet roller to contact the calibration plate using the height adjustment device, and adjust the outlet roller to contact the calibration plate using the height adjustment device; S4. Adjust the upper working roll again using the hydraulic cylinder adjustment assembly until the height of the upper working roll, the middle working roll, the inlet roll, and the outlet roll reaches the position of the heat straightening roll gap.

2. The roller gap calibration and operation method of a hot straightening machine according to claim 1, characterized in that, In step S1, the height of the inlet roller and the outlet roller is 4-8 mm lower than the height of several intermediate working rollers.

3. The roller gap calibration and operation method of a hot straightening machine according to claim 1, characterized in that, In step S2, the hydraulic cylinder adjustment assembly includes four straightening hydraulic cylinders. The extension and retraction ends of the four straightening hydraulic cylinders are all fixedly connected to an upper roller box. Several intermediate working rollers are arranged below the upper roller box. A first pressure sensor and a first displacement sensor are arranged on each of the four straightening hydraulic cylinders.

4. The roll gap calibration and operation method of a hot straightening machine according to claim 3, characterized in that, In step S2, the four straightening cylinders descend rapidly at a speed of 9-10 mm / s until they reach the deceleration position. Then, the four straightening cylinders descend slowly at a speed of 0.10-0.20 mm / s until the upper working roller contacts the upper surface of the calibration plate, thus entering the force control mode.

5. The roller gap calibration and operation method of a hot straightening machine according to claim 4, characterized in that, In step S2, under force control mode, the four straightening cylinders are adjusted so that the straightening force they detect reaches 500kN, so that the thickness of the current intermediate working roll and the upper working roll is the thickness of the calibration plate.

6. The roller gap calibration and operation method of a hot straightening machine according to claim 5, characterized in that, In step S2, the thickness of the calibration plate is 99 mm.

7. The roll gap calibration and operation method of a hot straightening machine according to claim 1, characterized in that, In step S3, the height adjustment device includes two adjusting cylinders, which are respectively located below the inlet roller and the outlet roller. Each adjusting cylinder has a first wedge at its telescopic end. A second wedge is slidably connected above the first wedge. The second wedge is located below the lower roller box. The inlet roller, the outlet roller, and several intermediate working rollers are located above the lower roller box.

8. The roll gap calibration and operation method of a hot straightening machine according to claim 7, characterized in that, In step S3, the adjusting cylinder below the inlet roller is extended and retracted to gradually raise the inlet roller to contact the calibration plate, so that the height difference between the current inlet roller and the intermediate working roller is 0.

9. The roll gap calibration and operation method of a hot straightening machine according to claim 8, characterized in that, In step S3, the adjusting cylinder below the exit roller is extended and retracted to gradually raise the exit roller until it contacts the calibration plate, so that the height difference between the current exit roller and the intermediate working roller is 0.

10. The roll gap calibration and operation method of a hot straightening machine according to claim 8, wherein in step S4, the height of the upper working roll is adjusted by the hydraulic cylinder adjustment assembly until the height difference between the upper working roll and the intermediate working roll, the inlet roll and the outlet roll is 140mm.

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