A method for determining and controlling the causes of wedge-shaped roll gaps in strip mills

Abstract

This invention discloses a method for determining and controlling the cause of wedge-shaped roll gaps in strip mills, comprising the following steps: First, determining whether the roll gap wedge shape is caused by the tilting of the lower support roll or by the cumulative wear and differential wear of the upper support roll bearing housing, AGC hydraulic cylinder, upper stepped pad, and other components on the operating and transmission sides; after determining the cumulative wear and differential wear of the upper support roll bearing housing, AGC hydraulic cylinder, upper stepped pad, and other components on the operating and transmission sides, using a technical solution to measure whether the upper support roll is tilted, further determining which component is worn, and a technical method for leveling the roll gap wedge shape, thus completely solving the roll gap wedge problem from its technical root; after determining that the lower support roll is tilted, further determining the cause of the tilting of the lower support roll, finally determining which component is worn, and a technical method for leveling the roll gap wedge shape, thus completely solving the roll gap wedge problem from its technical root.

Description

Technical Field

[0001] This invention belongs to the field of strip mill technology, specifically relating to a method for determining and controlling the causes of wedge-shaped roll gaps in strip mills. Background Technology

[0002] With the development of science and technology, modern rolling mill equipment is becoming increasingly sophisticated, and its process design and structural composition are becoming more complex. For example, each stand of the hot rolling F1-F7 finishing mill is assembled with components such as the gate on the operating side and the transmission side, upper pressure plate, upper step pad, AGC hydraulic cylinder and displacement sensor, upper support roll and bearing seat, upper support roll balance, upper work roll and bearing seat, lower work roll and bearing seat, lower support roll and bearing seat, lower step pad, equalizing plate, pressure head block, pressure plate, support seat, and gate on both sides of the rolling mill. These components are stacked and contacted vertically on both sides of the rolling mill to transmit rolling force.

[0003] Roll gap refers to the distance between the upper and lower work rolls of a rolling mill. Roll gap wedge shape refers to the difference in the distance between the two ends of the work roll along its length. Roll gap uniformity and levelness are crucial to ensuring the stability of rolling mill production and the quality of the strip shape. According to the rolling mill assembly design, the roll gap wedge shape value is measured and fed back by displacement sensors installed on two AGC hydraulic cylinders on the operating side and the drive side of the rolling mill.

[0004] Existing technologies can only measure and warn of roll gap wedges and temporarily adjust them to restore production. After temporary adjustments, the roll gap may no longer have a wedge shape or the wedge shape may become smaller, but the overall roll gap may still be tilted, affecting production stability. Furthermore, existing technologies cannot determine the specific cause of the roll gap wedge shape, i.e., whether it is caused by the tilt of the lower support roll or other reasons. This invention aims to solve this problem, providing a technical method to completely resolve the roll gap wedge problem at its root. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining and controlling the causes of wedge-shaped roll gaps in strip mills.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for determining and controlling the cause of wedge-shaped roll gap in strip mills, comprising the following steps:

[0007] 1) When the mill roll gap wedge value Δh appears, operate the AGC hydraulic cylinder, upper and lower work rolls, and upper and lower support rolls to make contact with the static pressure pad, and measure whether the upper support roll is tilted in the length direction. If it is tilted, it is determined that the lower support roll is tilted, and proceed to step 3); if it is not tilted, it is determined that the wear accumulation of the upper support roll bearing seat, AGC hydraulic cylinder and the above components on the operating side and the transmission side has a difference of Δh, and proceed to step 2).

[0008] 2) Given a displacement extension of 20mm for each of the AGC hydraulic cylinders in the rolling mill, operate the upper step pads of stages 1-3 in their working positions. Raise the upper support roller with the hydraulic balance cylinder until it is in close contact with the AGC hydraulic cylinder and the upper pressure plate. Measure the tilt of the upper support roller along its length. If the upper support roller tilts when the upper step pads of stages 1-3 are in their working positions, it is determined that there is a difference Δh in the cumulative wear of the upper support roller bearing housing, AGC hydraulic cylinder, and pressure plate at the top of the archway on both the operating and transmission sides. Correct the zero-position value adjustment wedge of the AGC hydraulic cylinder displacement sensor on the side with the larger displacement to resume production, i.e., add Δh to the original zero-position value. If the upper support roller tilts only when the upper step pad of a certain stage is in its working position, it is determined that there is a wear difference Δh between the step pads on the operating and transmission sides of this stage. Correct the zero-position value adjustment wedge of the AGC hydraulic cylinder displacement sensor on the side with the larger displacement to resume production. Replace this stage's step pad during maintenance.

[0009] 3) If the lower support roller is found to be tilted, adjust the zero value of the displacement sensor of the AGC hydraulic cylinder on the side with larger displacement to restore production; when stopping or repairing, with the lower step pads of grades 1-12 in the working position, measure the tilt of the lower support roller in the length direction; if the lower support roller is tilted when the step pads of grades 3 and above are in the working position, it is determined that there is a difference Δh in the cumulative wear of the lower support roller bearing seat and the components below on the operating side and the transmission side. Add shims Δh at the arc plate of the lower support roller bearing seat with lower elevation to temporarily correct and level the support roller, or precisely measure the wear of the arc plate of the lower support roller bearing seat, the pressure equalizing plate and the components below, and replace the excessively worn parts; if the lower support roller is tilted only when a certain grade of lower step pad is in the working position, it is determined that there is a wear difference Δh between the lower step pads of this grade on the operating side and the transmission side, and replace the lower step pad of this grade.

[0010] Specifically, Δh = |h operating side - h drive side| ≤ 2.5mm, where Δh is the roll gap wedge value; h = ΔOp + ΔPL, where h is the roll gap value, ΔOp is the distance from the upper work roll to the theoretical rolling line, and ΔPL is the distance between the theoretical rolling line and the actual rolling line; ΔPL = (T0 - T1 - T2) - D WB -D BB / 2-T S1 -T S2 T0 is the dimension from the theoretical rolling line to the bottom surface of the lower support of the archway; T1 is the dimension from the bottom surface of the support to the lower stepped pad; T2 is the dimension from the center line of the lower support roller bearing seat to the arc plate; D WB D represents the diameter of the lower work roll. BB T represents the diameter of the lower support roller. S1 T represents the thickness of the lower step pad. S2 The thickness of the arc-shaped plate of the lower support roller bearing seat is given; ΔOp=(H0-H1-H2-H3)-D WT -DBT / 2-ΔX-S, H0 is the theoretical rolling line dimension to the top surface of the archway, H1 is the AGC hydraulic cylinder plunger length dimension, H2 is the AGC hydraulic cylinder body bottom surface thickness dimension, H3 is the dimension from the center line of the upper support roller bearing seat to the top surface of the bearing seat, ΔX is the thickness dimension of the upper stepped pad and upper pressure plate, or the length of the mechanical pressing screw; D WT D represents the diameter of the upper working roller. BT This refers to the diameter of the upper support roller.

[0011] The present invention has the following beneficial effects: it can determine and control the specific causes of the roll gap wedge shape in strip mills, completely solve the roll gap wedge shape problem from the technical root, realize the uniformity and levelness of the roll gap value in the length direction, and ensure the stability of rolling production and the quality of product shape. Attached Figure Description

[0012] Figure 1 This is a flowchart of step 1) of the present invention.

[0013] Figure 2 This is a flowchart of step 2) of the present invention.

[0014] Figure 3 This is a flowchart of step 3) of the present invention. Detailed Implementation

[0015] The invention will now be described in further detail with reference to the accompanying drawings.

[0016] like Figure 1-3 A method for determining and controlling the cause of roll gap wedge shape in a strip mill is proposed. Based on the mill assembly design structure, a roll gap wedge calculation formula is constructed. The main factor affecting the roll gap wedge shape is the wear of various components that transmit rolling force in contact with each other in the vertical direction of the mill assembly. After it is found that the displacement measurement difference of the AGC hydraulic cylinder on the operating side and the transmission side exceeds the standard, step 1) is used to determine whether the roll gap wedge shape is caused by the tilt of the lower support roll or by the wear of the upper support roll bearing seat and above components. Then, step 2) is used to determine the specific wear location of the upper support roll bearing seat and above components. Then, step 3) is used to determine the specific cause and location of the tilt of the lower support roll. The wedge adjustment in steps 2) and 3) is divided into two steps: first, correcting the zero value of the displacement sensor of the AGC hydraulic cylinder on the side with larger displacement to adjust the wedge shape and temporarily restore production; second, finally determining the specific root cause component affecting the roll gap wedge shape and completely solving the problem from the perspective of maintenance technology.

[0017] Step 1) After discovering the mill roll gap wedge Δh, operate the AGC hydraulic cylinder, upper and lower work rolls, and upper and lower support rolls to make contact with the static pressure pad. Measure whether the upper support roll is tilted in the length direction. If tilting is present, determine that the lower support roll is tilted and proceed to step 3); if no tilting is present, determine that the wear accumulation of the upper support roll bearing seat, AGC hydraulic cylinder, and the above components on the operating side and transmission side has a difference Δh, and proceed to step 2).

[0018] Step 2) On the control panel, set the displacement extension of the AGC hydraulic cylinders of the mill to 20mm for each cylinder. Position the upper step pads (stages 1-3) in their working positions. Raise the upper support roll with the hydraulic balance cylinder until it is in close contact with the AGC hydraulic cylinder, upper step pad, and upper pressure plate. Measure the tilt of the upper support roll along its length. If the upper support roll is tilted when the upper step pads (stages 1-3) are in their working positions, it is determined that there is a difference Δh in the cumulative wear of the upper support roll bearing housing, AGC hydraulic cylinder, and pressure plate at the top of the mill on both the operating and transmission sides. Correct the AGC hydraulic cylinder on the side with the larger displacement. To restore production, the zero-point value of the cylinder displacement sensor is adjusted to a wedge shape, which means adding Δh to the original zero-point value. During maintenance, the wear of the upper support roller bearing seat, AGC hydraulic cylinder, and pressure plate at the top of the archway is precisely measured, and the excessively worn parts are replaced to completely solve the roll gap wedge problem. If the upper support roller is tilted when only a certain stage of the upper stepped pad is in the working position, it is determined that there is a wear difference Δh between the stepped pad on the operating side and the transmission side of this stage. The zero-point value of the AGC hydraulic cylinder displacement sensor on the side with larger displacement is adjusted to a wedge shape to restore production. During maintenance, the stepped pad of this stage is replaced to completely solve the roll gap wedge problem.

[0019] Step 3) Determine if the lower support roller is tilted, adjust the zero value of the displacement sensor of the AGC hydraulic cylinder on the side with larger displacement, and restore production; During shutdown or maintenance: Operate the lower step pads at positions 1-12 on the control panel to the working position, and measure the tilt of the lower support roller in the length direction; If the lower support roller is tilted when the third or higher step pads are in the working position, it is determined that there is a difference Δh in the cumulative wear of the lower support roller bearing seat and the components below it on the operating side and the transmission side. One solution is to temporarily correct and level the support roller by adding Δh pads at the arc plate of the lower support roller bearing seat with lower elevation; the other solution is to precisely measure the wear of the arc plate of the lower support roller bearing seat, the pressure equalizing plate and the components below it, and replace the excessively worn parts to completely solve the roll gap wedge problem; If the lower support roller is tilted only when a certain level of lower step pad is in the working position, it is determined that there is a wear difference Δh between the lower step pads on the operating side and the transmission side of this level, and replace this level of lower step pad to completely solve the roll gap wedge problem.

[0020] Based on the mill assembly design structure, the causes of the roll gap wedge shape are analyzed as follows: First, the lower support roll has an actual tilt, which causes the AGC hydraulic cylinder displacement output on the operating side and the drive side to be unequal when the upper and lower work rolls and support rolls are pressed against each other, resulting in a difference. This difference is the roll gap wedge shape. Second, the lower support roll does not have an actual tilt, but due to the cumulative wear and tear of the upper support roll bearing housing, AGC hydraulic cylinder, upper step pad and above components on the operating side and the drive side, the displacement output of the two AGC hydraulic cylinders is unequal, resulting in a difference.

[0021] Based on the total height of the archway window and the components that superimpose contact to transmit rolling force and affect the roll gap wedge shape, the calculation formula for the roll gap wedge shape is as follows:

[0022] 1) ΔPL=(T0-T1-T2)-D WB -D BB / 2-T S1 -T S2 .

[0023] In the formula, ΔPL is the distance between the theoretical rolling line and the actual rolling line;

[0024] T0: The theoretical distance from the rolling line to the bottom surface of the lower support of the archway;

[0025] T1: The dimension from the bottom of the support to the lower step pad;

[0026] T2: Dimension from the center line of the lower support roller bearing seat to the arc plate;

[0027] D WB : Diameter of the lower working roll;

[0028] D BB : Diameter of the lower support roller;

[0029] T S1 : Thickness of the lower step pad;

[0030] T S2 : Thickness dimension of the arc-shaped plate of the lower support roller bearing seat;

[0031] 2) ΔOp=(H0-H1-H2-H3)-D WT -D BT / 2-ΔX-S.

[0032] In the formula: ΔOp is the distance from the upper work roll to the theoretical rolling line.

[0033] H0: Theoretical distance from the rolling line to the top surface of the archway;

[0034] H1: Length of the plunger in the AGC hydraulic cylinder;

[0035] H2: Thickness of the bottom surface of the AGC hydraulic cylinder body

[0036] H3: Dimension from the centerline of the upper support roller bearing housing to the top surface of the bearing housing;

[0037] ΔX: Thickness of the upper step pad and upper pressure plate, or length of the mechanical pressing screw;

[0038] D WT : Diameter of the upper working roller;

[0039] D BT : Diameter of the upper support roller;

[0040] S: The extension amount of the AGC hydraulic cylinder plunger, measured by a displacement sensor installed on the AGC hydraulic cylinder;

[0041] 3) The roll gap value is h: h = ΔOp + ΔPL.

[0042] 4) Roll gap wedge value Δh, Δh=|h operating side - h drive side|≤2.5mm.

[0043] First, determine whether the roll gap wedge shape is caused by the tilt of the lower support roll, or by the cumulative wear and differences in the upper support roll bearing housing, AGC hydraulic cylinder, upper step pad, and other components on the operating and transmission sides.

[0044] After determining the cumulative wear and differences of the upper support roller bearing housing, AGC hydraulic cylinder, upper step pad and above components on the operating side and transmission side, a technical solution of measuring whether the upper support roller is tilted is adopted to further determine which component has worn, as well as the technical method of roller gap wedge leveling, to completely solve the roller gap wedge problem from the technical root.

[0045] After determining that the lower support roller is tilted, the cause of the tilt is further determined, and finally, it is determined which component is worn and the technical method for adjusting the roll gap wedge is determined, so as to completely solve the roll gap wedge problem from the technical root.

[0046] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0047] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for determining and controlling the causes of wedge-shaped roll gaps in strip mills, characterized in that, Includes the following steps: 1) When the mill roll gap wedge value Δh appears, operate the AGC hydraulic cylinder, upper and lower work rolls, and upper and lower support rolls to make static pressure contact. Measure whether the upper support roll is tilted in the length direction. If tilting exists, determine that the lower support roll is tilted and proceed to step 3). If no tilting exists, determine that the cumulative wear of the upper support roll bearing seat, AGC hydraulic cylinder and archway, upper pressure plate, upper stepped pad, and archway top pressure plate on the operating and transmission sides has a difference of Δh, and proceed to step 2). 2) Given a displacement extension of 20mm for each AGC hydraulic cylinder, with the upper step pads of levels 1-3 in their working positions, the hydraulic balance cylinder raises the upper support roller and presses it against the AGC hydraulic cylinder until it is in close contact with the upper step pad and the upper pressure plate. The tilt of the upper support roller in the length direction is measured. If the upper support rollers of levels 1-3 are tilted when the upper step pads are in their working positions, it is determined that there is a difference Δh in the cumulative wear of the upper support roller bearing seats, AGC hydraulic cylinders, and pressure plates on the top of the archway on the operating and transmission sides. The zero value of the displacement sensor of the AGC hydraulic cylinder on the side with the larger displacement is adjusted by wedge adjustment to restore production, that is, Δh is added to the original zero value. If the upper support rollers are tilted only when the upper step pads of a certain level are in their working positions, it is determined that there is a wear difference Δh between the step pads on the operating and transmission sides of this level. The zero value of the displacement sensor of the AGC hydraulic cylinder on the side with the larger displacement is adjusted by wedge adjustment to restore production. This level of step pad is replaced during maintenance. 3) If the lower support roller is found to be tilted, adjust the wedge shape to restore production by correcting the zero value of the displacement sensor of the AGC hydraulic cylinder on the side with larger displacement. When the machine is stopped or under maintenance, the lower step pads of grades 1-12 are in the working position, and the tilt of the lower support roller in the length direction is measured. If the lower support roller is tilted when the step pads of grades 3 and above are in the working position, it is determined that there is a difference Δh in the cumulative wear of the lower support roller bearing seat and the components below it on the operating side and the transmission side. Add shims Δh at the arc plate of the lower support roller bearing seat with lower elevation to temporarily correct and level the support roller, or precisely measure the wear of the arc plate of the lower support roller bearing seat, the pressure equalizing plate and the components below it, and replace the worn parts. If the lower support roller is tilted only when a certain grade of lower step pad is in the working position, it is determined that there is a wear difference Δh between the lower step pads on the operating side and the transmission side of this grade, and the lower step pad of this grade is replaced.

2. The method for determining and controlling the cause of wedge-shaped roll gap in a strip mill according to claim 1, characterized in that, The value of Δh = |h_operating_side - h_drive_side| ≤ 2.5 mm is the roll gap wedge value. h = ΔOp + ΔPL, where h is the roll gap value, ΔOp is the distance from the upper work roll to the theoretical rolling line, and ΔPL is the distance between the theoretical rolling line and the actual rolling line; ΔPL = (T0-T1-T2)-D WB - D BB / 2-T S1 -T S2 T0 is the dimension from the theoretical rolling line to the bottom surface of the lower support of the archway; T1 is the dimension from the bottom surface of the support to the lower stepped pad; T2 is the dimension from the center line of the lower support roller bearing seat to the arc plate; D WB D represents the diameter of the lower work roll. BB T represents the diameter of the lower support roller. S1 T represents the thickness of the lower step pad. S2 The thickness dimension of the arc-shaped plate of the lower support roller bearing seat; ΔOp = (H0-H1-H2-H3)-D WT -D BT / 2-ΔX-S, H0 is the theoretical rolling line dimension to the top surface of the archway, H1 is the AGC hydraulic cylinder plunger length dimension, H2 is the AGC hydraulic cylinder body bottom surface thickness dimension, H3 is the dimension from the center line of the upper support roller bearing seat to the top surface of the bearing seat, ΔX is the thickness dimension of the upper stepped pad and upper pressure plate, or the length of the mechanical pressing screw; D WT D represents the diameter of the upper working roller. BT S represents the diameter of the upper support roller, and S represents the extension amount of the AGC hydraulic cylinder plunger, which is measured by a displacement sensor mounted on the AGC hydraulic cylinder.

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