Calibration method for eliminating edge crack of working roll of roughing mill

Abstract

The invention relates to a calibration method for eliminating edge cracks of working rolls of a roughing mill. The calibration method comprises the steps that after a roll gap is adjusted till the sum of rolling force at the two ends of an upper working roll and a lower working roll is 2% larger than the maximum rolling force, electric pressing is stopped; adjusting the rolling force deviation of two ends of the upper and lower working rollers; adjusting the roll gap until the sum of the rolling forces at the two ends of the upper and lower working rolls is 30% of the maximum rolling force; adjusting the rolling force deviation of two ends of the upper and lower working rollers to be not greater than the maximum rolling force 1%; calibrating a roll gap between upper and lower working rolls; and confirming the actual roll gap between the upper and lower working rolls. The method has the advantages that according to a new design scheme, research of field actual conditions, equipment capacity analysis and determination of reprogramming of a calibration program, in the form of electric hydraulic mixed pressing of the hot rolling roughing mill, the phenomenon of edge cracking of the working roll is greatly reduced, the abrasion loss of the working roll is reduced, the service life of the working roll is prolonged, and the roughing mill calibration requirement is met; no new equipment is needed, no extra cost is needed, and the method is simple and has great popularization value.

Description

Technical Field

[0001] The invention relates to a calibration method for eliminating edge cracks of working rolls of a roughing mill. Background Art

[0002] The 2150 production line of a steel plant is a hot rolling production line with independent intellectual property rights. The 2150 rough rolling mill is an important equipment on the 2150 hot rolling production line. It is mainly used to roll continuous casting slabs into intermediate billets for finishing rolling. Therefore, the rough rolling mill is an important equipment to ensure the production capacity and product quality of the 2150 line. After the working rolls of the rough rolling mill were replaced, it was found that the edges of the old working rolls were cracked. In severe cases, the edges of the working rolls fell off, the loss of the working rolls increased, and the service life of the working rolls was affected; this led to an increase in the grinding of the rough rolling working rolls, and a reduction in the service life of the rough rolling working rolls, which brought huge losses to the production plant. Summary of the invention

[0003] The purpose of the present invention is to provide a calibration method for eliminating edge cracks of working rolls of a roughing mill, reduce edge cracks of working rolls, reduce wear of working rolls, and increase the service life of working rolls.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for eliminating edge cracks of a roughing mill work roll calibration, after the roll surfaces of the upper and lower work rolls are in direct contact, first eliminating the single-end force of the upper and lower work rolls, and then performing high-speed rotation calibration of the upper and lower work rolls, specifically comprising the following steps:

[0006] A method for eliminating edge cracks of a roughing mill work roll calibration, after the roll surfaces of the upper and lower work rolls are in direct contact, first eliminating the single-end force of the upper and lower work rolls, and then performing high-speed rotation calibration of the upper and lower work rolls, specifically comprising the following steps:

[0007] S1. The upper and lower working rolls are electrically pressed downward to adjust the roll gap until the sum of the rolling forces at both ends of the upper and lower working rolls is greater than 2% of the maximum rolling force of the roughing mill, and then the electric pressing is stopped. The maximum rolling force is 5000 tons;

[0008] S2. Adjust the roll gap deviation at both ends of the upper and lower working rolls so that the rolling force deviation at both ends of the upper and lower working rolls is not greater than 1% of the maximum rolling force of the roughing mill;

[0009] S3, start the main motor of the roughing mill, and make the working rolls of the roughing mill run at a speed of one third of the maximum speed (within an error of ±5%), and the maximum speed is 6 m / s;

[0010] S4, the upper and lower working rolls are hydraulically pressed downward to adjust the roll gap until the sum of the rolling forces at both ends of the upper and lower working rolls is equal to 30% of the maximum rolling force of the roughing mill;

[0011] S5. Adjust the roll gap deviation at both ends of the upper and lower working rolls so that the rolling force deviation at both ends of the upper and lower working rolls is not greater than 1% of the maximum rolling force of the roughing mill;

[0012] S6. When the sum of the rolling forces at both ends of the upper and lower working rolls is equal to 30% of the maximum rolling force, the sum of the electric pressing down and hydraulic pressing down magnetic scale position feedback is used as the reference value to calibrate the roll gap of the upper and lower working rolls, that is, the roll gap zero position of the upper and lower working rolls;

[0013] S7. Based on the zero position of the upper and lower working roll gaps, adjust the roll gap required during rolling. Deduct the feedback value calibrated at the zero position of the roll gap from the sum of the electric and hydraulic pressure magnetic scale position feedbacks to confirm the actual roll gap between the upper and lower working rolls.

[0014] In S1, the electric pressing is driven by the pressing motor driving the pressing screw.

[0015] In S1, the hydraulic pressure is driven by the servo valve controlling the hydraulic cylinder.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] According to the new design plan, the actual situation on site was studied, the equipment capacity was analyzed, and it was determined that the calibration procedure should be re-compiled. Under the form of electric-hydraulic mixed pressure of the hot rolling roughing mill, the phenomenon of edge cracks of the working rolls was greatly reduced, the wear of the working rolls was reduced, and the service life of the working rolls was increased. The calibration requirements of the roughing mill were met without adding new equipment or additional costs. The method is simple and has great promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the horizontal roll structure of the roughing mill.

[0019] Figure 2 It is the flow chart of improvement of calibration of horizontal rolls of roughing mill.

[0020] In the figure: 1-upper support roller balance 2-upper support roller 3-upper working roller 4-electric pressing screw 5-hydraulic pressing 6-lower working roller 7-lower support roller 8-lower step pad 9-lower step pad hydraulic cylinder 10-electric pressing motor. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0022] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0023] [Example 1]

[0024] By observing the working status of the working rolls, it was found that when the working rolls were calibrated, the upper working roll 3 and the lower working roll 6 were not in a straight line, and the upper working roll 3 and the lower working roll 6 were close to each other at high speed. After the roll surfaces of the upper working roll 3 and the lower working roll 6 were in direct contact, one end of the upper and lower working rolls came into contact first to generate rolling force, causing unbalanced force on the two ends of the upper and lower working rolls, resulting in edge wear and cracking. The calibration scheme of the working rolls of the rough rolling mill was redesigned to ensure that edge cracks of the working rolls are eliminated, the wear of the working rolls is reduced, the service life of the working rolls is increased, and the purpose of reducing costs and increasing efficiency is achieved. First, the causes of edge cracks on the upper working roll 3 and the lower working roll 6 of the roughing mill are analyzed. The roughing mill is a mixed pressing method of electric pressing 4 and hydraulic pressing 5. When the working rolls of the roughing mill are in normal production, the edges of the upper working roll 3 and the lower working roll 6 do not contact the slab, and the upper working roll 3 and the lower working roll 6 do not contact each other. Only when the working rolls of the roughing mill are calibrated, the upper working roll 3 and the lower working roll 6 are in contact for calibration, so the edge cracks of the upper working roll 3 and the lower working roll 6 are caused by calibration. After replacing the upper working roll 3 and the lower working roll 6, due to the change in roll diameter, it is necessary to re-determine the zero position of the contact roll gap between the upper working roll 3 and the lower working roll 6 to ensure the thickness of the slab rolled by the rolling mill.

[0025] See Figure 1A calibration method for eliminating edge cracks in the working rolls of a rough rolling mill. Since the edge cracks of the working rolls are caused by stress on the edges and high-speed rotation, the improvement is to first ensure that the roll surfaces of the upper working roll 3 and the lower working roll 6 are in full contact, eliminate the single-sided stress, and then perform high-speed rotation calibration. The position of the lower working roll 6 needs to be on the same horizontal plane as the rollers on both sides of the rolling mill. The horizontal state is achieved by adjusting the position of the lower step pad 8. The upper roll surface of the lower working roll is on the same horizontal line as the upper roll surfaces of the rollers on both sides of the rolling mill, ensuring smooth slab handling and rolling. The working roll calibration is achieved by adjusting the roll gap of the upper working roll 3. The upper working roll 3 and the lower working roll 6 first run at a high speed of 2 m / s. The upper working roll 3 is pressed by the electric press 4 to both sides of the upper and lower working rolls (the bearing boxes on both sides of the lower working roll are respectively provided with rolling force detection elements to detect the rolling forces on both sides of the upper and lower working rolls). The sum of the rolling forces is 100 tons. Then the hydraulic press 5 continues to press down. The rolling force PID controller controls the hydraulic servo valve, which is used to drive the hydraulic cylinder to adjust the extension position of the hydraulic press 5 hydraulic cylinder to achieve fast and static-free adjustment to both sides of the upper working roll 3 and the lower working roll 6. When the rolling force is 1500 tons and the rolling force deviation on both sides of the upper and lower working rolls is less than 50 tons, the position feedback of the electric press 4 lead screw and the hydraulic press 5 hydraulic cylinder is used as a reference to calibrate the working roll gap to "zero". Based on the zero roll gap, the actual roll gap between the upper and lower working rolls is confirmed by subtracting the feedback value calibrated when the roll gap is zero from the sum of the electric press and hydraulic press magnetic scale position feedback, and the roll gap required for rolling is adjusted. Edge cracks occur when the upper working roll 3 and the lower working roll 6 are replaced. The roll surfaces of the upper working roll 3 and the lower working roll 6 are not in a horizontal state. When the upper working roll 3 and the lower working roll 6 are running at high speed, the contact between the two sides of the roll surface is not synchronized, and one side contacts first, causing the edges of the upper working roll 3 and the lower working roll 6 to be stressed and rotate at high speed, resulting in large-scale edge cracks. Therefore, in order to reduce the impact, the rough rolling calibration method is optimized and improved, and the calibration technology of the upper working roll 3 and the lower working roll 6 of the rough rolling mill is updated.

[0026] The new technology solution is that the upper working roll 3 and the lower working roll 6 are pressed to both sides of the upper and lower working rolls by the electric pressing 4, and the rolling force is 100 tons. The rolling force deviation on both sides is detected to be no more than 50 tons. If the deviation is large, the roll gap deviation on both sides of the upper working roll 3 and the lower working roll 6 is adjusted to be reduced to the rolling force deviation on both sides is no more than 50 tons. After the rolling force is balanced, it is ensured that the roll surfaces of the working rolls are in good contact and that there is no single-sided contact between the roll surfaces of the upper working roll 3 and the lower working roll 6. Then the upper working roll 3 and the lower working roll 6 are restarted to run at a high speed of 2 meters per second, and the hydraulic pressing 5 is continued. The rolling force PID controller is used to control the hydraulic servo valve, adjust the extension position of the hydraulic 5 hydraulic cylinders, and achieve fast and static-free adjustment to reach the rolling force of 1500 tons on both sides of the upper working roll 3 and the lower working roll 6, and the rolling force deviation on both sides is less than 50 tons. The position feedback of the electric 4 screws and the hydraulic 5 hydraulic cylinders is used as a reference to calibrate the working roll gap to "0". Based on the 0 roll gap, the working roll gap is calibrated to "0". Based on the 0 roll gap, the roll gap is adjusted during rolling. Since the rolling force deviation on both sides has been eliminated before the upper working roll 3 and the lower working roll 6 are turned at high speed, the roll surface contact is guaranteed to be good, thereby eliminating the large-scale edge cracks caused by the single-end force and high-speed rotation of the upper working roll 3 and the lower working roll 6.

[0027] After determining the new automatic calibration scheme for the upper working roll 3 and the lower working roll 6 of the roughing mill, the automatic calibration program for the upper working roll 3 and the lower working roll 6 of the roughing mill was compiled. Through trial runs and debugging, the edge cracking of the upper working roll 3 and the lower working roll 6 has been greatly reduced, ensuring that the edge cracks of the upper working roll 3 and the lower working roll 6 are eliminated, reducing the wear of the upper working roll 3 and the lower working roll 6, and increasing the service life of the upper working roll 3 and the lower working roll 6, thereby achieving the goal of reducing costs and increasing efficiency.

Claims

1. A calibration method for eliminating edge cracks in a roughing mill work roll, characterized in that: After the roll surfaces of the upper and lower working rolls are in direct contact, the single-end force of the upper and lower working rolls is eliminated first, and then the high-speed rotation calibration of the upper and lower working rolls is performed, which specifically includes the following steps: S1, the upper and lower working rolls are electrically pressed down to adjust the roll gap downward until the sum of the rolling forces at both ends of the upper and lower working rolls is greater than 2% of the maximum rolling force of the roughing mill, and then the electric pressing is stopped; S2. Adjust the roll gap deviation at both ends of the upper and lower working rolls so that the rolling force deviation at both ends of the upper and lower working rolls is not greater than 1% of the maximum rolling force of the roughing mill; S3, start the main motor of the roughing mill to make the working rolls of the roughing mill run at one third of the maximum speed; S4, the upper and lower working rolls are hydraulically pressed downward to adjust the roll gap until the sum of the rolling forces at both ends of the upper and lower working rolls is equal to 30% of the maximum rolling force of the roughing mill; S5. Adjust the roll gap deviation at both ends of the upper and lower working rolls so that the rolling force deviation at both ends of the upper and lower working rolls is not greater than 1% of the maximum rolling force of the roughing mill; S6. When the sum of the rolling forces at both ends of the upper and lower working rolls is equal to 30% of the maximum rolling force, the sum of the electric pressing down and hydraulic pressing down magnetic scale position feedback is used as the reference value to calibrate the roll gap of the upper and lower working rolls, that is, the roll gap zero position of the upper and lower working rolls; S7. Based on the zero position of the upper and lower working roll gaps, adjust the roll gap required during rolling. Deduct the feedback value calibrated at the zero position of the roll gap from the sum of the electric and hydraulic pressure magnetic scale position feedbacks to confirm the actual roll gap between the upper and lower working rolls.

2. A calibration method for eliminating edge cracks in a roughing mill work roll according to claim 1, characterized in that: In S1, the electric pressing is driven by the pressing motor driving the pressing lead screw.

3. A calibration method for eliminating edge cracks in a roughing mill work roll according to claim 1, characterized in that: In S1, the hydraulic pressure is driven by a servo valve controlling a hydraulic cylinder.

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