A detection method for preventing hot rolled strip from carrying foreign matter into a finishing mill

Abstract

The present invention discloses a detection method for preventing foreign matter from entering a finishing mill with a hot-rolled steel strip, comprising the following steps: 1) the roll gap position sensors of the inlet and outlet pinch rollers perform self-checking, if the self-checking is normal, then go to step 2), if the self-checking is abnormal, then report an error; 2) the roll gap position sensors of the inlet and outlet pinch rollers perform self-scanning detection, and detect whether the roll gap jump of the inlet and outlet pinch rollers is normal; 3) the upper computer sends given data and compares the difference with the feedback value of the roll gap position sensor, and determines whether the roll gap position sensor has a jump; 4) the torque current of the inlet and outlet pinch rollers is load monitored and detected, and it is determined whether the torque current is greater than the rated current; 5) when any step from step 2) to step 4) is abnormal, it is determined that there is a phenomenon of shearing the head and tail of the strip. The present invention avoids the scrap steel accident caused by the flying shear blade adhering to the edge material of the head and tail of the strip, and entering the finishing mill due to missed detection.

Description

Technical Field

[0001] The invention relates to a hot-rolled steel strip production technology, and more particularly to a detection method for preventing foreign matter in a hot-rolled steel strip from entering a finishing mill. Background Art

[0002] At present, in the production process of hot-rolled strip, there is no detection and corresponding control method for the shearing head and tail phenomenon, and there is no effective detection of whether there is flying shear adhesion to the head and tail of the strip and the control strategy for the corresponding finishing mill. If the flying shear blade is found to be sticking to the head and tail of the strip, it can only be identified by the operator's eyes. However, relying on this human eye recognition method alone not only increases the operator's labor load, but also easily leads to missed judgments. Therefore, scrap steel caused by the strip entering the finishing mill due to missed detection of the flying shear blade adhesion to the head and tail phenomenon on the production line often occurs. The flying shear equipment at the entrance of the finishing mill often causes the flying shear blade to stick to the head and tail of the strip when it is cut due to abnormal drum transmission, abnormal shear blade, iron sticking, etc. When the next strip enters the flying shear area, the flying shear drum will pre-swing and shear, and the head and tail of the previous strip will fall on the current strip. When the current strip enters the finishing mill for rolling, it is bound to cause abnormal rolling force, abnormal roll gap, rolling breakage and other scrap steel phenomena in the finishing mill. The waste steel treatment caused by such situations takes a long time, is difficult to handle, and has high risks, which has a serious negative impact on normal production. Summary of the invention

[0003] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a detection method for preventing hot-rolled strip with foreign matter from entering the finishing mill, so as to avoid scrap steel accidents caused by the edge material of the strip head and tail sticking to the flying shear blade and entering the finishing mill due to missed detection.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A detection method for preventing foreign matter from entering a finishing mill with a hot-rolled steel strip comprises the following steps:

[0006] 1) The roller gap position sensors of the inlet and outlet pinch rollers perform self-test. If the self-test is normal, proceed to step 2). If the self-test is abnormal, an error is reported;

[0007] 2) The roller gap position sensors of the inlet and outlet pinch rollers perform self-scanning detection to detect whether the roller gap runout of the inlet and outlet pinch rollers is normal;

[0008] 3) The upper computer sends the given data and compares the difference with the feedback value of the roll gap position sensor to determine whether the roll gap position sensor has a jump;

[0009] 4) Carry out load monitoring and detection on the torque current of the inlet and outlet pinch rollers to determine whether the torque current is greater than the rated current;

[0010] 5) When any of steps 2) to 4) is abnormal, it is determined that the tape head and tape tail are cut.

[0011] Preferably, in step 1), the roller gap position sensors of the inlet and outlet pinch rollers perform self-checking as follows:

[0012] When the roll gap feedback of the roll gap position sensor satisfies x∈[x1+α,x2+α], it means that the self-test is normal;

[0013] In the above formula, x represents the roll gap feedback of the roll gap position sensor, with a value range of x∈[-25,160], x1 represents the lower limit of the roll gap of the pinch roller, with a value range of x1∈[-25,10], x2 represents the theoretical maximum roll gap opening data of the pinch roller, with a value range of x2∈[145,160], and α represents the adjustment amount of the upper and lower limits.

[0014] Preferably, in step 2), the roller gap position sensors of the inlet and outlet pinch rollers perform self-scanning detection as follows:

[0015] Obtain the sampling data of two adjacent scanning cycles, subtract the sampling data of the previous scanning cycle from the sampling data of the next scanning cycle, and obtain the deviation change value of each scanning cycle interval △ α ,Right now:

[0016] △ α =|θ n -θ n-1 |, unit: mm

[0017] In the above formula, θ n Indicates the sampling data of the next scanning cycle, in mm; θ n-1 Indicates the sampling data of the previous scanning cycle, in mm;

[0018] Get the maximum speed of the cylinder of the pinch roller in a single scanning cycle θ vmax ,Right now:

[0019] Unit: mm

[0020] In the above formula, V represents the maximum movement speed of the pinch roller cylinder, in mm / s;

[0021] when When the roller gap runout of the inlet and outlet pinch rollers is judged to be abnormal;

[0022] k represents the abnormal bounce coefficient, and its value range is 0.95~1.15.

[0023] Preferably, in step 3), the upper computer sends the given data and compares the difference with the feedback value of the roll gap position sensor as follows:

[0024] when When the roller gap position sensor is judged to have a jump;

[0025] In the above formula, θ n Indicates the feedback value of the roll gap position sensor, θ r Indicates that the host computer sends the given data. It indicates the ratio coefficient based on the given value of the roll gap, that is, the ratio coefficient of the given roll gap. This coefficient is used to adjust the threshold value. The value range is 0.15~0.25.

[0026] Preferably, in step 4), it is determined whether the torque current is greater than the rated current, that is:

[0027] L1 ≥ λL n

[0028] In the above formula, L1 represents the torque current of the inlet and outlet pinch rollers, L n represents the rated current, λ represents the correction factor, and its value range is 1.5~2.5.

[0029] Preferably, it is characterized in that the step 5) further comprises:

[0030] When the roll gap runout of the inlet and outlet pinch rolls meets any of the following conditions: when; and / or

[0031] when when; and / or

[0032] When L1 ≥ λL n hour;

[0033] That is, it is determined that there is a phenomenon of cutting the head and tail of the strip, and a fault alarm box pops up on the human-machine interface to remind the operator to open the descaling box at the finishing rolling entrance and check whether there are foreign objects in the strip.

[0034] The present invention provides a detection method for preventing foreign objects in hot-rolled strip from entering a finishing mill. The present invention uses the torque current of the motor of the pinch roller of the dephosphorization box at the finishing entrance and the special data changes and jumps of the position sensor to identify whether there is a flying shear strip head and tail, and immediately uses an HMI pop-up box alarm to prompt the operator to remove the phosphorus box area to check whether there is foreign objects, thereby avoiding scrap steel accidents caused by the flying shear blades adhering to the strip head and tail and then missing detection and entering the finishing mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1It is a schematic diagram of the arrangement of sensors in a descaling box used in a detection method for preventing foreign matter in a hot-rolled steel strip from entering a finishing mill according to the present invention;

[0036] Figure 2 It is a schematic flow chart of a detection method for preventing foreign matter in hot-rolled strip from entering a finishing mill according to the present invention. DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0038] Please combine Figure 1 and Figure 2 As shown, the present invention provides a detection method for preventing foreign matter from entering the finishing mill with hot-rolled steel strip, which uses the motor torque current of the inlet and outlet pinch rollers 1 and 2 in the dephosphorization box (located between the flying shear device 100 and the finishing mill 200) at the finishing entrance and the special data changes and jumps of the corresponding roll gap position sensors 3 and 4 to identify whether the strip 300 has a flying shear strip head and tail, and specifically includes the following steps:

[0039] 1) The roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 perform self-test. If the self-test is normal, proceed to step 2). If the self-test is abnormal, an error is reported;

[0040] 2) The roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 perform self-scanning detection to detect whether the roller gap runout of the inlet and outlet pinch rollers 1 and 2 is normal;

[0041] 3) The upper computer sends the given data and compares the difference with the feedback values ​​of the roll gap position sensors 3 and 4 to determine whether the roll gap position sensors 3 and 4 have a jump;

[0042] 4) Perform load monitoring and detection on the torque current of the inlet and outlet pinch rollers 1 and 2 to determine whether the torque current is greater than the rated current;

[0043] 5) When any of steps 2) to 4) is abnormal, it is determined that the tape head and tape tail are cut.

[0044] In the above step 1), the roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 perform self-test as follows:

[0045] When the roll gap feedback of the roll gap position sensors 3 and 4 satisfies x∈[x1+α,x2+α], it means that the self-test is normal and can meet the detection conditions of the flying shear belt head and tail;

[0046] In the above formula, x represents the roll gap feedback of the roll gap position sensors 3 and 4, x1 represents the roll gap lower limit of the inlet and outlet pinch rollers 1 and 2, x2 represents the theoretical maximum roll gap opening data of the inlet and outlet pinch rollers 1 and 2, and α represents the adjustment amount of the upper and lower limits;

[0047] The value range of x is x∈[-25,160], and the value of this embodiment is -20mm;

[0048] The value range of x1 is x1∈[-25,10], and the value of this embodiment is 5mm;

[0049] The value range of x2 is x2∈[145,160], and the value of x2 in this embodiment is 150mm.

[0050] In the above step 2), the roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 perform self-scanning detection as follows:

[0051] When the roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 are self-checked normally, the sampling data of two adjacent scanning cycles are obtained, and the sampling data of the latter scanning cycle is subtracted from the sampling data of the previous scanning cycle to obtain the deviation change value of each scanning cycle interval △ α , use △ α The stabilizer model is established based on the change in the amount of the inlet and outlet pinch rollers 1 and 2 to detect whether the roll gap runout is normal, and then to identify whether the strip 300 has the head and tail of the flying shear. That is:

[0052] △ α =|θ n -θ n-1 |, unit: mm

[0053] In the above formula, θ n Indicates the sampling data of the next scanning cycle, in mm; θ n-1 Indicates the sampling data of the previous scanning cycle, in mm;

[0054] Then obtain the maximum speed of the cylinder of the pinch roller in a single scanning cycle Right now:

[0055] Unit: mm

[0056] In the above formula, V represents the maximum movement speed of the pinch roller cylinder, in mm / s;

[0057] In this embodiment, V is set to 30 mm / s, so the above calculation formula gives The maximum value is 1.5mm.

[0058] Theoretically, when When , it can be shown that the bounce amount of the roller gap exceeds the maximum speed of its cylinder action, and the inlet and outlet pinch rollers 1 and 2 may be passively lifted after being hit, so it is considered that there is a possibility that the head and tail of the flying shear strip have entered the descaling box. However, in order to improve the detection accuracy, the abnormal bounce coefficient k of the strip hitting the pinch roller is introduced. In this embodiment, k is taken as 1.08, and it can be obtained:

[0059] Then the formula is derived as:

[0060]

[0061] k represents the abnormal bounce coefficient, and its value range is 0.95~1.15.

[0062] That is to say, when When the roller gap runout of the inlet and outlet pinch rollers 1 and 2 is judged to be abnormal, it is further judged that the flying shear belt head and tail phenomenon has occurred.

[0063] In the above step 3), the upper computer sends the given data and compares the difference with the feedback value of the roll gap position sensor as follows:

[0064] when When the roller gap position sensors 3 and 4 are judged to have jump changes;

[0065] In the above formula, θ n Indicates the feedback value of the roll gap position sensors 3 and 4, θ r Indicates that the host computer sends the given data. It indicates the ratio coefficient based on the given value of the roll gap, that is, the ratio coefficient of the given roll gap. This coefficient is used to adjust the threshold value. The value range is 0.15~0.25.

[0066] In the above step 4), the torque current of the inlet and outlet pinch rollers 1 and 2 is used for load monitoring detection. Under normal rolling conditions, the current torque of the motor inverter 5 of the inlet and outlet pinch rollers 1 and 2 is L1, and the rated current L of the motor is n , when the F1 stand of the finishing mill 200 bites the steel and the descaling roller speed detection (obtained from the descaling roller motor inverter 6) is in a non-zero speed state:

[0067] v PR ≥v ST

[0068] In the above formula, v PR Indicates the speed feedback of the inlet and outlet pinch rollers 1 and 2, v ST Indicates the non-zero speed setting threshold value, the value range is 0.01m / s~0.05m / s;

[0069] At this time, when L1≥λL n At the same time, a minor fault alarm box pops up on the human-machine interface HMI screen to remind the operator to open the descaling box at the finishing entrance and check whether there are foreign objects such as heads and tails on the strip 300.

[0070] In the above formula, L1 represents the torque current of the inlet and outlet pinch rollers, L n Indicates rated current, λ indicates correction factor, ranging from 1.5 to 2.5;

[0071] The above step 5) further comprises:

[0072] Edit the PLC controller function program, use the closed-loop detection and judgment of the roll gap setting and feedback, and the logical interlocking conditions of the judgment are as follows: use the "normally closed" signal of the pinch roll APC (automatic position control) operation as the interlocking condition, and use the "normally open" signal of the pinch roll constant pressure after the F1 frame bites the steel as the interlocking condition. That is to say, when the pinch roll is in the non-automatic position control operation state, and the pinch roll is in the synchronous constant pressure pinching state of the finishing mill, the following detection judgment is met:

[0073] When satisfied When the strip is 300, a minor fault alarm box pops up on the human-machine interface HMI screen to remind the operator to open the descaling box at the finishing entrance and check whether there are foreign objects such as the head and tail of the strip 300.

[0074] When the roller gap position sensors 3 and 4 of the inlet and outlet pinch rollers 1 and 2 are self-checked normally, use the following logic detection method to write the corresponding PLC controller function program:

[0075] When the roll gap runout of the inlet and outlet pinch rollers 1 and 2 simultaneously satisfies the logical "or" relationship (either the roll gap runout of the inlet and outlet pinch rollers 1 and 2 satisfies the logical "or" relationship) When the strip is running, a minor fault alarm pops up on the human-machine interface (HMI) to remind the operator to open the descaling box at the finishing entrance and check whether there are foreign objects such as the head and tail of the strip 300.

[0076] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A detection method for preventing foreign matter from entering a finishing mill with a hot-rolled steel strip, characterized in that: The following steps are involved: 1) The roller gap position sensors of the inlet and outlet pinch rollers perform self-test. If the self-test is normal, proceed to step 2). If the self-test is abnormal, an error is reported; 2) The roller gap position sensors of the inlet and outlet pinch rollers perform self-scanning detection to detect whether the roller gap runout of the inlet and outlet pinch rollers is normal; 3) The upper computer sends the given data and compares the difference with the feedback value of the roll gap position sensor to determine whether the roll gap position sensor has a jump; 4) Carry out load monitoring and detection on the torque current of the inlet and outlet pinch rollers to determine whether the torque current is greater than the rated current; 5) When any of the steps 2) to 4) is abnormal, and it is determined that the tape head and tail are cut, In the step 1), the roller gap position sensors of the inlet and outlet pinch rollers perform self-test as follows: When the roll gap feedback of the roll gap position sensor satisfies x∈[x1+α,x2+α], it means that the self-test is normal; In the above formula, x represents the roll gap feedback of the roll gap position sensor, with a value range of x∈[-25,160], x1 represents the lower limit of the roll gap of the pinch roller, with a value range of x1∈[-25,10], x2 represents the theoretical maximum roll gap opening data of the pinch roller, with a value range of x2∈[145,160], and α represents the adjustment amount of the upper and lower limits. In step 2), the roller gap position sensors of the inlet and outlet pinch rollers perform self-scanning detection as follows: Obtain the sampling data of two adjacent scanning cycles, subtract the sampling data of the previous scanning cycle from the sampling data of the next scanning cycle, and obtain the deviation change value Δ of each scanning cycle interval α ,Right now: D α =|θ n -θ n-1 |, unit mm In the above formula, θ n Indicates the sampling data of the next scanning cycle, in mm; θ n-1 Indicates the sampling data of the previous scanning cycle, in mm; Get the maximum speed of the cylinder of the pinch roller in a single scanning cycle θ vmax ,Right now: θ vmax =V÷20, unit: mm In the above formula, V represents the maximum movement speed of the pinch roller cylinder, in mm / s; when When the roller gap runout of the inlet and outlet pinch rollers is judged to be abnormal; k represents the abnormal bounce coefficient, and its value range is 0.95~1.

15.

2. The detection method for preventing foreign matter in hot-rolled steel strip from entering a finishing mill according to claim 1, characterized in that: In the step 3), the upper computer sends the given data and compares the difference with the feedback value of the roll gap position sensor as follows: When θ n ≥lθ r When the roller gap position sensor is judged to have a jump; In the above formula, θ n Indicates the feedback value of the roll gap position sensor, θ r It indicates that the upper computer sends the given data, l indicates the ratio coefficient based on the given value of the roll gap, that is, the ratio coefficient of the given roll gap. This coefficient is used to adjust the threshold value, and the value range of l is 0.15~0.

25.

3. The detection method for preventing foreign matter in hot-rolled steel strip from entering a finishing mill according to claim 1, characterized in that: In step 4), it is determined whether the torque current is greater than the rated current, that is: L1≥λL n In the above formula, L1 represents the torque current of the inlet and outlet pinch rollers, L n represents the rated current, λ represents the correction factor, and its value range is 1.5 to 2.

5.

4. The detection method for preventing foreign matter in a hot-rolled steel strip from entering a finishing mill according to any one of claims 1 to 3, characterized in that: The step 5) further comprises: When the roll gap runout of the inlet and outlet pinch rolls meets any of the following conditions: and / or When θ n ≥lθ r and / or When L1 ≥ λL n hour; That is, it is determined that there is a phenomenon of cutting the head and tail of the strip, and a fault alarm box pops up on the human-machine interface to remind the operator to open the descaling box at the finishing rolling entrance and check whether there are foreign objects in the strip.

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