A method for identifying the accident risk of hot-rolled camber in cold rolling

Abstract

The present invention relates to a method for identifying the risk of cold rolling cavity opening accidents caused by hot rolling camber, including steps such as reading, screening data, and making judgments according to strip specifications. The method for identifying the risk of cold rolling cavity opening accidents caused by hot rolling camber provided by the present invention obtains the center line offset data of the hot rolling incoming material, and based on this, is used to identify the overall morphological characteristics of the external appearance of the hot rolling incoming material, mainly to judge whether there are serious defects in the shape of the strip, which are manifested in the form of camber and are caused by the asymmetric extension of the strip along the width direction during the hot rolling process; this method can effectively identify the camber defects of the hot rolling incoming material, and conduct early risk warning for the cavity opening accidents and adverse effects on rolling stability that may be caused by this curve in cold rolling, so as to intervene in advance.

Description

Technical Field

[0001] The present invention relates to a method for identifying the accident risk of cold rolling cavity opening caused by hot rolling camber, belonging to the technical field of automatic control. Background Art

[0002] Camber, also known as side bend, is a phenomenon in which the strip steel bends in the horizontal direction. There are many factors affecting the camber of hot-rolled strip steel. During the on-site rolling process, there are always some asymmetric factors that cause changes in the set process parameters of rolling. These mainly include three aspects: incoming material factors; equipment factors, and working condition factors. These influencing factors will all lead to the asymmetry of the rolling state along the axis of the roll, resulting in differences in the reduction rate along the width direction of the rolling mill, thus generating camber.

[0003] Common incoming material factors include: billet wedge shape. During the rolling process, the longitudinal thickness cannot be evenly controlled, and the vertical pressure distribution along the axis of the roll becomes asymmetric. As a result, the reduction rate of the rolled piece in the transverse direction is different. The metal on the thicker side will flow to the other side, and finally the rolled piece will shift to the side with a smaller reduction rate, resulting in the camber phenomenon; the center line of the rolled piece is offset. During the rolling process of the rolled piece, when the slab is not centered during biting and runs off, the forces on both sides of the rolling mill are unbalanced, and the rolling force distribution is also uneven and asymmetric. As a result, the slab will shift to the side with a smaller reduction amount during the rolling process, and finally the camber appears.

[0004] Common equipment factors include: the stiffness difference between the two sides of the rolling mill. When the longitudinal stiffness of the two sides of the rolling mill is different, it seriously affects the symmetric and uniform distribution of the rolling force. The greater the stiffness, the more difficult it is for the roll to tilt. The springback of the side with a large longitudinal stiffness of the rolling mill becomes smaller, its reduction amount becomes larger, the outlet thickness on this side becomes smaller, while the outlet thickness on the other side becomes larger, thus resulting in camber; the levelness of the rolling mill and the difference in transverse reduction. If the carriage at the bottom of the rolling mill is not level, the underpad of the backup roll is uneven or broken, or the roll grinding wear is uneven, etc., resulting in differences in the levelness of the rolling mill, thus causing the distribution of the roll gap to be asymmetric, and there will also be differences in the reduction amounts on both sides of the rolled piece, so it is easy to appear camber; the roll profile. When the loaded crown of the work roll is a positive crown, the synthesis of the roll gap crown will make the slab deviate more from the center line, exacerbating the degree of camber and the bending direction is more random and more difficult to control.

[0005] The temperature distribution in the width direction of the rolled piece is uneven. For example, during the heating process of the slab in the heating furnace, incorrect centering causes uneven heating at different positions, the distribution and flushing of the roll cooling water are uneven, the water leakage during the fine descaling process results in uneven temperature distribution of the rolled piece, and the uneven distribution of the gap of the water dividing plate in the width direction causes uneven temperature distribution of the rolled piece, etc. The uneven temperature distribution of the rolled piece in the width direction makes the deformation resistance at different positions different. The side with a higher slab temperature has a smaller deformation resistance, a smaller rolling force, a larger reduction, a higher exit speed, and a smaller exit thickness, ultimately causing the rolled piece to show a sickle bend phenomenon.

[0006] The sickle bend defect not only affects the shape and dimensional quality of the finished strip steel, but also affects the rolling stability during the subsequent cold rolling process. In severe cases, it may even lead to a cavity opening accident. Therefore, it is necessary to identify and judge the sickle bend defect of the hot-rolled incoming material before cold rolling to carry out risk pre-control. The center line offset data of the strip steel can be measured at the exit position of the last hot rolling stand, and this data can well reflect the external morphology of the hot-rolled incoming material. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: to overcome the above-mentioned technical drawbacks and provide a risk identification method for hot-rolled sickle bend to cold rolling cavity opening accidents based on the full-length center line offset data of hot-rolled incoming materials.

[0008] To solve the above technical problems, the technical solution proposed by the present invention is: a risk identification method for hot-rolled sickle bend to cold rolling cavity opening accidents, including the following steps:

[0009] Step 1: According to the cold rolling production plan, read the center line offset data Cen of the full length range measured at the hot rolling exit of the strip steel to be cold rolled i (i = 1, 2, 3,..., n), where i is the position along the length direction of the strip steel;

[0010] Step 2: Before the strip steel enters cold rolling, shear the parts with abnormal head and tail quality. The shearing length of the head is Cut h , and the shearing length of the tail is Cut t ;

[0011] Step 3: According to the head and tail shearing lengths of the strip steel, process the read center line offset data Cen of the strip steel i (i = 1, 2, 3,..., n), and remove the data of the head and tail shearing length parts in the data to obtain the center line offset data Cen i (i = Cut h + 1, Cut h + 2,..., n - Cut t );

[0012] Step 4: After the strip removes the head shearing length, according to the strip specifications, use the formula: len h =[0.05Wid set -15Thk set to calculate the length len h that needs attention at the head. Wid set is the target width of the strip in the hot rolling process, and Thk set is the target thickness of the strip in the hot rolling process;

[0013] Step 5: According to the head shearing length and the length that needs attention at the head of the strip, obtain the center line offset data of the length that needs attention at the head:

[0014] Step 6: After the strip removes the tail shearing length, according to the strip specifications, use the formula: len t =[0.06Wid set -15Thk set to calculate the length len t that needs attention at the tail;

[0015] Step 7: According to the tail shearing length and the length that needs attention at the tail of the strip, obtain the center line offset data of the length that needs attention at the tail:

[0016] Step 8: According to the strip specifications, calculate the maximum value ΔCen set that the center line offset range within any 5 meters of the length that needs attention at the head and the length that needs attention at the tail can allow: ΔCen set =[90Thk set -0.1Wid set ;

[0017] Step 9: Extract the center line offset data within any 5 meters of the length that needs attention at the head, and calculate the maximum value and the minimum value among them;

[0018] Among them, Cut h +1≤i≤Cut h +len h -5;

[0019] Among them, Cut h +1≤i≤Cut h +len h -5;

[0020] is the maximum value among the centerline offset data of any 5 meters within the length of the head that requires attention, and a is the position coordinate of the maximum value in the strip length direction. is the minimum value among the centerline offset data of any 5 meters within the length of the head that requires attention, and b is the position coordinate of the minimum value in the strip length direction;

[0021] Step 10: Calculate whether the difference between the maximum value and the minimum value among the centerline offset data of any 5 meters within the length of the head that requires attention satisfies: When it is satisfied, there is a risk of cavity opening in the S1 stand of the cold tandem mill within the range of m to n at the head of the strip;

[0022] Step 11: Extract the centerline offset data of any 5 meters within the length of the tail that requires attention, and calculate the maximum value and the minimum value therein;

[0023] where, n - Cut t - len t +1 ≤ i ≤ n - Cut t - 4;

[0024] where, n - Cut t - len t +1 ≤ i ≤ n - Cut t - 4;

[0025] is the maximum value among the data of any 5 meters within the length of the tail that requires attention, and the subscript x is the position coordinate of the maximum value in the strip length direction, is the minimum value among the data of any 5 meters within the length of the tail that requires attention, and the subscript y is the position coordinate of the minimum value in the strip length direction;

[0026] Step 12: Calculate whether the difference between the maximum value and the minimum value among the centerline offset data of any 5 meters within the length of the tail that requires attention satisfies: When it is satisfied, there is a risk of cavity opening in the S1 stand of the cold tandem mill within the range of x to y at the tail of the strip.

[0027] A further improvement of the above solution is that in the above Step 1, the data interval in the centerline offset data is 1 meter.

[0028] The method for identifying the risk of cold rolling cavity opening accidents caused by hot rolling camber provided by the present invention obtains the center line offset data of hot rolling incoming materials, and based on this, identifies the overall morphological characteristics of the external appearance of hot rolling incoming materials, mainly judging whether there are serious defects in the shape of the strip steel in the form of camber caused by the asymmetric extension of the strip steel along the width direction during the hot rolling process; this method can effectively identify the camber defects of hot rolling incoming materials, and conduct early risk warnings for the possible cavity opening accidents caused by this curve in cold rolling and the adverse effects on rolling stability, so as to intervene in advance. Specific implementation mode

[0029] Embodiment

[0030] The method for identifying the risk of cold rolling cavity opening accidents caused by hot rolling camber in this embodiment includes the following steps:

[0031] Step 1: According to the cold rolling production plan, read the center line offset data Cen within the full length range measured at the hot rolling outlet of the strip steel to be cold rolled i (i = 1, 2, 3,..., n), where i is the position along the length direction of the strip steel; according to the detection frequency and accuracy of the detection equipment, the distance between two adjacent positions in the length direction is usually 1 m;

[0032] Step 2: Before the strip steel enters cold rolling, shear the parts with abnormal head and tail quality. The shearing length at the head is Cut h , and the shearing length at the tail is Cut t ;

[0033] Step 3: According to the head and tail shearing lengths of the strip steel, process the read center line offset data Cen i (i = 1, 2, 3,..., n), and remove the data of the head and tail shearing lengths in the data to obtain the center line offset data Cen i (i = Cut h + 1, Cut h + 2,..., n - Cut t );

[0034] Step 4: After removing the head shearing length of the strip steel, according to the specifications of the strip steel, use the formula: len h = [0.05Wid set - 15Thk set to calculate the length len h that needs attention at the head. Wid set is the target width of the strip steel in the hot rolling process, and Thk set is the target thickness of the strip steel in the hot rolling process;

[0035] Step 5: Obtain the centerline offset data of the length requiring attention at the head according to the head shearing length of the strip steel and the length requiring attention at the head:

[0036] Step 6: After removing the tail shearing length of the strip steel, according to the specifications of the strip steel, use the formula: len t = [0.06Wid set - 15Thk set , calculate the length len t that requires attention at the tail;

[0037] Step 7: Obtain the centerline offset data of the length requiring attention at the tail according to the tail shearing length of the strip steel and the length requiring attention at the tail:

[0038] Step 8: According to the specifications of the strip steel, calculate the maximum value ΔCen set that the centerline offset range can allow within any 5 meters of the length requiring attention at the head and the length requiring attention at the tail: ΔCen set = [90Thk set - 0.1Wid set ;

[0039] Step 9: Extract the centerline offset data within any 5 meters of the length requiring attention at the head, and calculate the maximum value and the minimum value among them;

[0040] Among them, Cut h + 1 ≤ i ≤ Cut h + len h - 5;

[0041] Among them, Cut h + 1 ≤ i ≤ Cut h + len h - 5;

[0042] is the maximum value of the centerline offset data within any 5 meters of the length requiring attention at the head, a is the position coordinate of the maximum value in the strip steel length direction, is the minimum value of the centerline offset data within any 5 meters of the length requiring attention at the head, b is the position coordinate of the minimum value in the strip steel length direction;

[0043] Step 10: Calculate whether the difference between the maximum value and the minimum value of the centerline offset data within any 5 meters of the length requiring attention at the head satisfies: When it is satisfied, there is a risk of cavity in the S1 stand of the tandem cold rolling within the range of m to n at the head of the strip steel;

[0044] Step 11: Extract the centerline offset data for any 5 meters within the length of interest at the tail, and calculate the maximum and minimum values among them;

[0045] where, n-Cut t -len t +1 ≤ i ≤ n-Cut t -4;

[0046] where, n-Cut t -len t +1 ≤ i ≤ n-Cut t -4);

[0047] is the maximum value among the data for any 5 meters within the length of interest at the tail, and the subscript x is the position coordinate of the maximum value in the strip length direction, is the minimum value among the data for any 5 meters within the length of interest at the tail, and the subscript y is the position coordinate of the minimum value in the strip length direction;

[0048] Step 12: Calculate whether the difference between the maximum and minimum values of the centerline offset data for any 5 meters within the length of interest at the tail satisfies: When it is satisfied, there is a risk of cavity opening in the S1 stand of the cold tandem mill within the range from x to y at the strip tail.

[0049] The following is illustrated by taking the products in an actual production line as an example.

[0050] The length of the incoming strip is 900 m, the set width in the hot rolling process is 1000 mm, the set thickness is 2 mm, and the head and tail shearing lengths are both 4 m.

[0051] (1) According to the cold rolling production plan, read the centerline offset data Cen of the full length measured at the hot rolling exit for the strip to be put on line i (i = 1, 2, 3,..., 900);

[0052] (2) Cut h = Cut t = 4;

[0053] (3) According to the head and tail shearing lengths of the hot rolled incoming material, process the read centerline offset data Cen of the hot rolled incoming material i (i = 1, 2, 3,..., 900), and remove the partial data of the head and tail shearing lengths from this data to obtain Cen i (i = 5, 6,..., 896);

[0054] (4) For the head, there is: len h = [0.05Widset -15 Thk set =[0.05×1000 - 15×2]=20; That is, the length that needs attention at the head is 20 m;

[0055] (5) At the head, there is:

[0056] (6) At the tail, there is: len t =[0.06 Wid set -15 Thk set =[0.06×1000 - 15×2]=30; That is, the length that needs attention at the tail is 30 m;

[0057] (7)

[0058] (8) ΔCen set =[90 Thk set -0.1 Wid set =[90×2 - 0.1×1000]=80 mm;

[0059] (9) According to the offset data of the partial center line in the length direction of the incoming material:

[0060] Position i (m) 5 6 7 8 9 10 11 <![CDATA[Cen i (mm)]]> -25.1 -6.5 10.3 44.2 60.2 65.3 63.2 Position i (m) 12 13 14 15 16 17 18 <![CDATA[Cen i (mm)]]> 57.5 65.6 70.4 45.2 15.5 -10.2 -5.2 Position i (m) 19 20 21 22 23 <![CDATA[Cen i (mm)]]> 2.5 5.6 10.4 14.2 8.5

[0061] Then in the range of 5 - 9 m:

[0062]

[0063]

[0064] In the range of 14 - 18 m:

[0065]

[0066]

[0067] (10) Among the data in the above two groups:

[0068]

[0069]

[0070] (11) Since the range of variation in both of the above two groups of data exceeds the limit, the ranges of 5 - 9 m and 14 - 17 m at the head are both risk areas.

[0071] (12) The judgment of the tail risk is similar to that of the head, and no detailed example is given here.

[0072] Thus far, the risk positions of the complete camber at the head and tail of a hot-rolled incoming material for a cold rolling cavity-opening accident can be obtained.

[0073] The present invention is not limited to the above embodiments. Any technical solution formed by equivalent replacement falls within the protection scope required by the present invention.

Claims

1. A method for identifying the accident risk of camber in hot rolling for cold rolling cavity opening, characterized in that, It includes the following steps: Step 1: According to the cold rolling production plan, read the center line offset data Cen within the full length range measured at the hot rolling outlet of the strip to be cold rolled i (i = 1, 2, 3, ..., n), where i is the position along the length direction of the strip Step 2: The strip is sheared for the parts with abnormal head and tail quality before entering cold rolling, and the shearing length at the head is Cut h , and the shearing length at the tail is Cut t ; Step 3: Process the center line offset data Cen of the read strip steel according to the head and tail shearing lengths of the strip steel i (i = 1, 2, 3,..., n), remove the data of the head and tail shearing lengths in the data to obtain the center line offset data Cen i (i = Cut h +1, Cut h +2,..., n - Cut t ); Step 4: After the head shearing length of the strip is removed, according to the strip specifications, use the formula: len h = 0.05Wid set - 15Thk set to calculate the length len h that needs attention at the head. Wid set is the target width of the strip in the hot rolling process, and Thk set is the target thickness of the strip in the hot rolling process; Step 5: Obtain the center line offset data of the length to be concerned about at the head according to the head shearing length and the length to be concerned about required at the head of the strip steel: Step 6: After removing the tail shear length of the strip, according to the specifications of the strip, use the formula: len t = 0.06Wid set - 15Thk set , calculate the length len t that needs attention at the tail; Step 7: Obtain the center line offset data of the tail length to be concerned about according to the tail shearing length of the strip steel and the length to be concerned about at the tail: Step 8: According to the specifications of the strip steel, calculate the maximum value ΔCen that can be allowed for the range of centerline offset within any 5 meters of the length to be concerned at the head and the length to be concerned at the tail set : ΔCen set = 90Thk set - 0.1Wid set ; Step 9: Extract the centerline offset data of any 5 meters within the length of interest at the head, and calculate the maximum and minimum values among them; Among them, Cut h +1 ≤ i ≤ Cut h + len h - 5; Among them, Cut h +1 ≤ i ≤ Cut h + len h - 5; is the maximum value among the centerline offset data for any 5-meter length within the length of the head that requires attention, and a is the position coordinate of the maximum value in the strip length direction. is the minimum value among the centerline offset data for any 5-meter length within the length of the head that requires attention, and b is the position coordinate of the minimum value in the strip length direction. Step 10: Calculate whether the difference between the maximum value and the minimum value among the centerline offset data of any 5 meters in the length that needs attention at the head meets the following condition: When it meets the condition, there is a risk of cavity opening in the S1 stand of the cold tandem mill within the range from a to b at the head of the strip steel. Step 11: Extract the centerline offset data of any 5 meters within the length of interest at the tail, and calculate the maximum and minimum values among them; Among them, n-Cut t -len t +1 ≤ i ≤ n-Cut t -4; Among them, n-Cut t -len t +1 ≤ i ≤ n-Cut t -4; is the maximum value among the data of any 5-meter segment within the length of the tail that requires attention. The subscript x is the position coordinate of the maximum value in the strip length direction. is the minimum value among the data of any 5-meter segment within the length of the tail that requires attention. The subscript y is the position coordinate of the minimum value in the strip length direction. Step 12: Calculate whether the difference between the maximum value and the minimum value of the centerline offset data of any 5 meters in the length that needs attention at the tail meets the following condition: When it meets the condition, there is a risk of cavity opening in the S1 stand of the tandem cold rolling mill within the range of x to y at the tail of the strip steel.

2. The method for identifying the accident risk of hot-rolled camber on cold rolling cavity according to claim 1, characterized in that: In the said Step 1, the data interval in the centerline offset data is 1 meter.

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