Method for reducing the indentation of foreign matter on the lower surface of hot-rolled strip steel

Abstract

The present application relates to a kind of methods for reducing the foreign matter of hot-rolled strip lower surface press-in, comprising: 1) lifting rough rolling mill rack vertical roll middle part lower transition plate elevation: lower transition plate elevation lifting distance=(the standard height of rolling elevation line-lower transition plate elevation) / 2;2) adjusting vertical roll roller lower shoulder: vertical roll roller working surface bottom rolling elevation value is lower than the elevation value of rolling line, and satisfy: the elevation value of rolling line-vertical roll roller working surface bottom rolling elevation value=40~48mm;Vertical roll roller lower shoulder bevel angle is 23±2°.Advantages are: after using the method of the present application, tail foreign matter press-in and scratch defect disappear, reduce the quantity of tail foreign matter press-in and scratch defect in warehouse to be repaired, while improving the time of coil backlog volume, reduce the probability of blocking warehouse, ensure that coil is rolled into coil, first time delivery, ensure contract execution rate.

Description

Technical Field

[0001] This invention belongs to the field of rolling auxiliary equipment, and particularly relates to a method for reducing the indentation of foreign objects on the lower surface of hot-rolled strip steel. Background Technology

[0002] Hot-rolled strip steel may have quality defects such as foreign objects being pressed in or scratches during the production process, which will affect product quality, reduce product yield, and require rework. This will in turn affect the overall yield, reduce scrap rate, and restrict production line costs.

[0003] Foreign object indentation mainly occurs at the edges of the strip, and all of them occur on the lower surface of the strip. By conducting macroscopic morphology, microstructure and composition analysis on the locations where foreign object indentation defects occur on the surface of hot-rolled plates, the causes and processes of the defects were identified. In conjunction with the on-site production process and equipment status investigation, it was further clarified that the cause of foreign object indentation is due to equipment aging and long-term disrepair of spare parts, mainly changes in the shape and position of the vertical rolls, which leads to foreign object indentation and scratch defects at the tail of the strip on the 2300 production line. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reducing the indentation of foreign objects on the lower surface of hot-rolled strip steel, solving the problems of foreign object indentation and scratches on the lower surface of hot-rolled strip steel, and eliminating related problems caused by foreign object indentation on the lower surface of strip steel.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for reducing foreign matter indentation on the lower surface of hot-rolled strip steel includes:

[0007] 1) Increase the elevation of the lower transition plate at the middle section of the vertical rolls on the roughing mill stand:

[0008] Lower transition plate elevation increase distance = (standard height of rolling elevation line - lower transition plate elevation) / 2;

[0009] 2) Adjust the lower shoulder of the vertical roll:

[0010] The bottom rolling elevation of the vertical roll working surface is lower than the rolling line elevation, and the following conditions are met:

[0011] Rolling line elevation value - bottom rolling elevation value of the vertical roll working surface = 40~48mm;

[0012] The angle of the lower shoulder slope of the vertical roll is 23±2°.

[0013] This also includes adjusting the position of the vertical roller bearing housing accessories:

[0014] The height of the bottom of the lower shoulder of the vertical roll - the height of the top of the lower platform of the vertical roll bearing housing accessory = 10~14mm.

[0015] This also includes adjusting the opening degree of the vertical rollers on the frame for the second pass:

[0016] When the strip width is less than or equal to 1800 mm, the opening of the second pass of the rolling mill is 149-151 mm;

[0017] When the strip width is greater than 1800mm, the opening of the second pass of the rolling mill is 79-81mm.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] After adopting the method of the present invention, the defects of foreign objects pressing in and scratching at the tail end disappear, reducing the number of steel coils with foreign objects pressing in and scratching at the tail end that need to be repaired in the warehouse. At the same time, it increases the time that steel coils stay in the warehouse, reduces the probability of warehouse blockage, and ensures that steel coils are shipped as soon as they are rolled into coils, thus ensuring the contract execution rate.

[0020] To prevent slabs from impacting the mill stand rolls and causing foreign matter on the lower surface, the elevation of the lower transition plate in the middle of the vertical rolls is raised. Considering that the lower transition plate in the middle of the vertical rolls is 20mm below the rolling line elevation and that the transition plate itself is subject to wear, specific values ​​were obtained through calculations corresponding to the maintenance cycle and the wear of the lower transition plate. Adjusting the lower shoulder of the vertical rolls can reduce the prolonged contact between the lower shoulder of the vertical rolls and the edge of the slab, thus reducing the defects of foreign matter on the lower surface of the strip. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the installation position of the lower transition plate.

[0022] Figure 2 This is a schematic diagram showing the positions of the lower shoulder of the vertical roll and the lower platform of the vertical roll bearing housing.

[0023] In the diagram: 1-rolling mill archway; 2-pad plate; 3-lower transition plate; 4-rolling elevation line; 5-vertical roll working surface; 6-vertical roll lower shoulder slope; 7-vertical roll bearing seat accessory lower platform; 8-lower shoulder arc elevation. Detailed Implementation

[0024] The present invention will now be described in detail 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.

[0025] A method to reduce foreign object intrusion on the lower surface of hot-rolled strip steel, while ensuring mill capacity and various functions, involves adjusting the elevation of the lower transition plate 3 inside the roughing mill stand, as well as the dimensions of the lower shoulder of the vertical roll and the accessories of the vertical roll bearing seat. This addresses the issue of excessively large mill roll spacing (approximately 3m) between the lower transition plate 3 and the stands, which can cause malfunctions when the strip is fastened, edge defects during normal production, and direct contact between the strip edge and the working surface of the vertical roll after entering the mill. The method prevents deformation and scratches caused by the strip edge contacting the lower shoulder of the vertical roll or the accessories of the vertical roll bearing seat, thus avoiding foreign object intrusion. Specifically, the method includes:

[0026] 1) See Figure 1 Raise the elevation of the lower transition plate 3 in the middle of the vertical roll section of the roughing mill stand, and reduce the height difference between the rolling elevation line 4 and the lower transition plate 3:

[0027] The elevation increase distance of the lower transition plate = 1 / 2 (standard height of the rolling elevation line - elevation of the lower transition plate);

[0028] In practice, the pad 2 can be directly welded onto the transition plate in the middle of the vertical roll of the roughing mill stand.

[0029] 2) Adjust the lower shoulder of the vertical roll, see Figure 2 :

[0030] If the rolling elevation value 8 at the bottom of the vertical roll working surface is lower than the rolling elevation line value 4, then lower the arc elevation value 8 between the lower working surface and the lower shoulder of the vertical roll:

[0031] Rolling line elevation value - bottom rolling elevation value of vertical roll working surface = 40mm;

[0032] The angle of the lower shoulder slope of the vertical roll is increased from 12° to 23±2°.

[0033] 3) See Figure 2 Adjust the position of the vertical roll bearing housing attachment so that the height of the lower shoulder of the vertical roll is higher than the top height of the lower platform 7 of the vertical roll bearing housing attachment, and satisfy the following:

[0034] The height of the bottom of the lower shoulder of the vertical roll - the height of the top of the lower platform of the vertical roll bearing housing = 10mm.

[0035] 4) Adjust the opening degree of the vertical rollers on the frame for the second pass:

[0036] When the strip width is less than or equal to 1800 mm, the opening of the second pass of the rolling mill is increased from 50 mm to 150 mm;

[0037] When the strip width is greater than 1800mm, the opening of the second pass of the rolling mill is increased from 50mm to 80mm.

Claims

1. A method for reducing the indentation of foreign objects on the lower surface of hot-rolled strip steel, characterized in that, include: 1) Increase the elevation of the lower transition plate at the middle section of the vertical rolls on the roughing mill stand: Lower transition plate elevation increase distance = (standard height of rolling elevation line - lower transition plate elevation) / 2; 2) Adjust the lower shoulder of the vertical roll: The bottom rolling elevation of the vertical roll working surface is lower than the rolling line elevation, and the following conditions are met: Rolling line elevation value - bottom rolling elevation value of the vertical roll working surface = 40~48mm; The angle of the lower shoulder slope of the vertical roll is 23±2°.

2. The method for reducing the indentation of foreign objects on the lower surface of hot-rolled strip steel according to claim 1, characterized in that, This also includes adjusting the position of the vertical roller bearing housing accessories: The height of the bottom of the lower shoulder of the vertical roll - the height of the top of the lower platform of the vertical roll bearing housing accessory = 10~14mm.

3. The method for reducing the indentation of foreign objects on the lower surface of hot-rolled strip steel according to claim 1, characterized in that, This also includes adjusting the opening degree of the vertical rollers on the frame for the second pass: When the strip width is less than or equal to 1800 mm, the opening of the second pass of the rolling mill is 149-151 mm; When the strip width is greater than 1800mm, the opening of the second pass of the rolling mill is 79-81mm.

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