A calibration method for eliminating edge cracks in the work rolls of a roughing mill

Abstract

The present invention relates to a calibration method for eliminating edge cracks in the working rolls of a roughing mill, comprising: adjusting the sum of the rolling forces from the roll gap to the ends of the upper and lower working rolls to be greater than 2% of the maximum rolling force, and then stopping the electric pressure reduction; adjusting the rolling force deviation at both ends of the upper and lower working rolls; adjusting the sum of the rolling forces from the roll gap to the ends of the upper and lower working rolls to be equal to 30% of the maximum rolling force; adjusting the rolling force deviation at both ends of the upper and lower working rolls to be no greater than 1% of the maximum rolling force; calibrating the roll gaps of the upper and lower working rolls; and confirming the actual roll gap between the upper and lower working rolls. The advantages of the present invention are: based on a new design scheme, research on actual site conditions, and equipment capacity analysis, the calibration program is re-compiled to significantly reduce the phenomenon of edge cracks in the working rolls, reduce the wear of the working rolls, and increase the service life of the working rolls under the form of electric and hydraulic mixed pressure reduction in the hot rolling roughing mill, meeting the calibration requirements of the roughing mill, without adding new equipment or incurring additional costs, and the method is simple and has great promotion value.

Description

Technical Field

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

[0002] A steel mill's 2150 production line is a hot rolling line with proprietary intellectual property rights. The 2150 roughing mill is a key piece of equipment on the line, primarily used to roll continuous-cast slabs into intermediate bars for finishing rolling. Therefore, the roughing mill is crucial for ensuring the production capacity and product quality of the 2150 line. After replacing the roughing mill's work rolls, cracks were observed on the edges of the old work rolls. In severe cases, the edges of the work rolls could even chip, increasing wear and shortening their service life. This resulted in increased wear on the roughing rolls, shortening their lifespan and causing significant losses to the mill. 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, thereby reducing edge cracks of working rolls, reducing wear of working rolls and increasing 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 in a roughing mill work roll calibration method includes eliminating the single-end force of the upper and lower work rolls after the roll surfaces of the upper and lower work rolls are in direct contact, and then performing high-speed rotation calibration of the upper and lower work rolls. The method specifically includes the following steps:

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

[0007] S1. The upper and lower working rolls are electrically pressed down 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. Then the electric pressing is stopped. The maximum rolling force is 5000 tons.

[0008] S2. Adjust the gap deviation between the upper and lower working rolls so that the rolling force deviation between the upper and lower working rolls is no more 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 no more 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 work rolls is equal to 30% of the maximum rolling force, the sum of the electric and hydraulic pressure scale position feedback is used as the reference value to calibrate the upper and lower work roll gaps, which is the zero position of the upper and lower work roll gaps;

[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 hydraulic cylinder controlled by the servo valve.

[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, and the equipment capacity was analyzed. It was determined that the calibration procedure should be re-compiled. Under the form of electric and hydraulic mixed pressure of the hot rolling roughing mill, the phenomenon of edge cracking of the working roll was greatly reduced, the wear of the working roll was reduced, the service life of the working roll was increased, and the calibration requirements of the roughing mill were met. There is no need to add new equipment or increase 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 roller structure of the roughing mill.

[0019] Figure 2 This is the flow chart for improving the calibration of the horizontal rolls of the 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 will be described in detail below with reference to 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 under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection 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, which made the forces at both ends of the upper and lower working rolls unbalanced, causing edge wear and cracking. The calibration scheme of the working rolls of the roughing mill was redesigned to ensure that the edge cracks of the working rolls were eliminated, the wear of the working rolls was reduced, the service life of the working rolls was increased, and the purpose of reducing costs and increasing efficiency was achieved. First, the cause of edge cracks on the upper working roll 3 and the lower working roll 6 of the roughing mill was analyzed. The roughing mill uses a mixed reduction method of electric reduction 4 and hydraulic reduction 5. During normal production, the edges of the upper working roll 3 and the lower working roll 6 do not contact the slab, nor do the upper working roll 3 and the lower working roll 6. Only when the roughing mill working rolls are calibrated do the upper working roll 3 and the lower working roll 6 contact for calibration. Therefore, the edge cracks on 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, the zero position of the contact roll gap between the upper working roll 3 and the lower working roll 6 needs to be re-determined due to the change in roll diameter to ensure the thickness of the slab rolled by the rolling mill.

[0025] See Figure 1A calibration method for eliminating edge cracks in the roughing mill work rolls. Since edge cracks in the work 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 work roll 3 and the lower work roll 6 are in full contact, eliminate the single-sided stress, and then perform high-speed rotation calibration. The position of the lower work roll 6 needs to be on the same horizontal plane as the roller tables 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 work roll is on the same horizontal line as the upper roll surfaces of the roller tables on both sides of the rolling mill, ensuring smooth slab handling and rolling. The work roll calibration is achieved by adjusting the roll gap of the upper work 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 to both sides of the upper and lower working rolls by the electric press 4 (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. The hydraulic servo valve 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 at this time is used as a reference to calibrate the work 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 roughing 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, the contact of the working roll surfaces is ensured to be good, and the roll surfaces of the upper working roll 3 and the lower working roll 6 are ensured to have no unilateral contact. 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 and adjust the extension position of the hydraulic pressing 5 hydraulic cylinder to achieve fast and static-free adjustment to achieve a 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 pressing 4 screw and the hydraulic pressing 5 hydraulic cylinder at this time is used as a reference to calibrate the work roll gap to "0". Based on the 0 roll gap, the work 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 high-speed slewing of the upper working roll 3 and the lower working roll 6, good contact between the roll surfaces is ensured, thereby eliminating the large-scale edge cracks caused by the upper working roll 3 and the lower working roll 6 being subjected to single-end force and rotating at high speed.

[0027] After determining the new automatic calibration scheme for the upper working roll 3 and the lower working roll 6 of the roughing mill, an 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 phenomenon 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 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. The specific steps include: S1. The upper and lower working rolls are electrically pressed down 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; S2. Adjust the gap deviation between the upper and lower working rolls so that the rolling force deviation between the upper and lower working rolls is no more 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 no more 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 work rolls is equal to 30% of the maximum rolling force, the sum of the electric and hydraulic pressure scale position feedback is used as the reference value to calibrate the upper and lower work roll gaps, which is the zero position of the upper and lower work roll gaps; 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: The electric pressing in the above steps is driven by the pressing motor driving the pressing screw.

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

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