A method of discriminating characteristics of a rolling mill motor

Abstract

This invention discloses a method for determining the characteristics of a rolling mill motor, comprising the following steps: determining the rolling specifications, steel grade, process, and rolling mill stand; accumulating the actual speed drop values ​​and actual recovery cycles corresponding to different specifications, steel grades, and rolling speeds; setting a speed drop value fluctuation threshold; setting a recovery cycle fluctuation threshold; and setting a motor characteristic discrimination mechanism based on the speed drop value fluctuation threshold and the recovery cycle fluctuation threshold. This invention enables the discrimination and control of rolling mill motor characteristics, thereby predicting the real-time status of the rolling mill motor in advance. When the motor characteristics change beyond a safety threshold, an early alarm is triggered, thus avoiding the failure of preset impact compensation and reducing the probability of safety accidents.

Description

Technical Field

[0001] This invention relates to a method for determining electrode characteristics, and more particularly to a method for determining the characteristics of a rolling mill motor, belonging to the field of steel rolling technology. Background Technology

[0002] When hot steel enters the rolling mill, it exerts an impact force on the rolls, causing a sudden drop in roll speed. Therefore, in the automated rolling control process, there is a so-called "impact compensation," which is a pre-emptive speed increase compensation performed by the rolling mill before the hot steel enters, thus compensating for the speed drop when the rolling mill is impacted. Impact compensation is especially important in the high-speed range where rolling speeds are even higher. Without impact compensation, speed differences can easily occur, causing hot steel to pile up and resulting in production accidents.

[0003] The characteristics of electric motors can be categorized as follows: 1. Mechanical characteristics, involving motor speed, torque, and efficiency; 2. Dynamic characteristics, including starting and braking characteristics. Starting characteristics mainly focus on the process from a static to a dynamic state, including starting time, starting current, and torque. For bar mill production lines, the characteristics of the rolling mill motor, to a certain extent, determine the stability of the rolling mill during the rolling process. In particular, the actual speed reduction caused by red steel impact rolling mills will change with the motor characteristics, thus causing the set impact compensation to fail. However, currently, there are no good means to monitor motor characteristics in real time and thus predict or maintain them in advance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for determining the characteristics of a rolling mill motor, thereby realizing the determination of motor characteristics.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for determining the characteristics of a rolling mill motor includes the following steps: S1. Determine the specifications, steel grade, process, and mill stand for rolling; S2. Accumulate the actual values ​​of speed drop and actual recovery cycles corresponding to different specifications, steel grades, and rolling speeds; S3. Set the threshold for rapid descent value fluctuation; S4. Set the recovery cycle fluctuation threshold; S5. Set a motor characteristic discrimination mechanism based on the speed drop value fluctuation threshold and the recovery cycle fluctuation threshold.

[0007] Further, step S1 specifically involves: determining the rolling specifications, rolling steel grade, mill stand number, mill incoming material temperature T1, and actual mill speed V0.

[0008] Further, step S2 specifically involves: for a rolling mill stand, under different rolling specifications, rolling steel grades, and rolling mill incoming material temperature T1, setting a speed drop setpoint X, recording the actual speed drop value XL and actual recovery cycle TL fed back by the motor sensor, and establishing a first calculation table using these data. According to the data in the first calculation table, when the rolling specification, rolling steel grade, and mill stand number are fixed values, the actual descent value XL is related to the mill incoming material temperature T1, the actual recovery period TL is related to the actual descent value XL, and the matching degree between the descent set value X and the actual descent value XL is related to the rolling steel grade. Therefore, when the speed drop setting value X in the first calculation table is equal to the actual speed drop value XL, the speed drop setting value X at this time is used as the final impact compensation value XB, and the corresponding actual recovery period is TB. At this time, the red steel will neither pile up nor pull up.

[0009] Furthermore, step S3 specifically involves: as the service life of the motor increases, the rigidity of the motor will decrease, and the actual value of the speed drop will increase. Calculate the absolute value A of the head-to-tail drop difference under different actual drop values ​​XL. Take a drop of length L from the head of the red steel and measure its weight M1. Take a drop of length L from the tail of the red steel and measure its weight M2. Then the absolute value A of the head-to-tail drop difference is A = |M1-M2| / M1. When A = 1%, the corresponding minimum actual drop value is XL1 and the maximum actual drop value is XL2. Then the drop value fluctuation threshold α = [XL1-XB, XL2-XB] and record the drop value fluctuation threshold α in the first calculation table.

[0010] Furthermore, step S4 specifically involves: as the motor's usage cycle increases, the motor's start-up time and braking characteristics will decrease, thus increasing the actual recovery cycle. The actual recovery period TL and the measured absolute value A of the head and tail strip difference are calculated under different usage time conditions of the rolling mill. When A=1%, the actual recovery period is TL. Then the recovery period fluctuation threshold β=TL-TB and the recovery period fluctuation threshold β is recorded in the first calculation table.

[0011] Further, step S5 specifically involves: for a rolling mill with a newly replaced motor, by using its rolling specifications, rolled steel grade, rolling mill stand, rolling mill incoming material temperature, and actual rolling mill speed, the impact compensation value XB, speed drop value fluctuation threshold α, and recovery cycle fluctuation threshold β corresponding to the first calculation table are found. When the current actual speed drop value XL-XB > α, a motor rigidity abnormality alarm signal is issued; when the current actual recovery cycle TL-TB > β, a motor start-up time and braking characteristic abnormality alarm signal is issued.

[0012] Compared with the prior art, the present invention has the following advantages and effects: The present invention provides a method for judging the characteristics of a rolling mill motor, which can realize the judgment and control of the characteristics of the rolling mill motor, thereby predicting the real-time status of the rolling mill motor in advance, and alarming in advance when the motor characteristics change beyond the safety threshold, thereby avoiding the failure of the preset impact compensation and reducing the probability of safety accidents. Attached Figure Description

[0013] Figure 1 This is a flowchart of a method for determining the characteristics of a rolling mill motor according to the present invention.

[0014] Figure 2 This is a schematic diagram of the first calculation table according to an embodiment of the present invention.

[0015] Figure 3 This is a table showing the actual value of the speed drop XL and the measured absolute value of the head and tail tube difference A in an embodiment of the present invention.

[0016] Figure 4 This is a table showing the actual recovery cycle and the measured absolute value A of the head and tail bar difference of the motor under different time conditions according to embodiments of the present invention.

[0017] Figure 5 This is a state diagram of a complete normal steel-biting action according to an embodiment of the present invention.

[0018] Figure 6 This is a state diagram of a motor when its stiffness decreases according to an embodiment of the present invention.

[0019] Figure 7 This is a state diagram of an embodiment of the present invention when the motor stiffness is normal and the braking characteristics decrease. Detailed Implementation

[0020] To illustrate in detail the technical solutions adopted by the present invention to achieve the intended technical objectives, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Furthermore, the technical means or technical features in the embodiments of the present invention can be replaced without creative effort. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1 As shown, a method for determining the characteristics of a rolling mill motor according to the present invention includes the following steps: S1. Determine the specifications, steel type, process, and mill stand for rolling.

[0022] Step S1 specifically involves determining the rolling specifications, rolling steel grade, mill stand number, mill incoming material temperature T1, and actual mill speed V0.

[0023] S2. Accumulate the actual values ​​of speed drop and actual recovery cycles corresponding to different specifications, steel grades, and rolling speeds.

[0024] Step S2 is as follows: For a rolling mill stand, under the premise of different rolling specifications, rolling steel grades, and rolling mill incoming material temperature T1, a speed drop setpoint X is set, the actual speed drop value XL and the actual recovery cycle TL fed back by the motor sensor are recorded, and these data are used to establish the first calculation table.

[0025] According to the data in the first calculation table, when the rolling specification, rolling steel grade, and mill stand number are fixed values, the actual descent value XL is related to the mill incoming material temperature T1, the actual recovery period TL is related to the actual descent value XL, and the matching degree between the descent set value X and the actual descent value XL is related to the rolling steel grade.

[0026] Therefore, when the speed drop setting value X in the first calculation table is equal to the actual speed drop value XL, the speed drop setting value X at this time is used as the final impact compensation value XB, and the corresponding actual recovery period is TB. At this time, the red steel will neither pile up nor pull up.

[0027] This embodiment uses a 20-gauge, 7-stand rolling mill as an example. The incoming material temperature for the 6-stand mill is approximately 1000℃, and the actual mill speed is 922 rpm. A speed drop setting value X is set. The online motor is a new piece of equipment. The actual speed drop value XL and the actual recovery period TL are calculated. The following can be obtained: Figure 2 The first calculation table is shown.

[0028] As shown in the table above, the descent rate is related to the incoming material temperature, the recovery cycle is related to the actual descent rate, and the matching degree between the set descent rate and the actual descent rate is mainly related to the steel grade being rolled. Temperature matching relates to the material's plasticity; the higher the temperature, the lower the plasticity and the smaller the impact force. Based on the above data, it can be inferred that setting the impact compensation for 7 runs of the 400 series and 20 specifications at 8 rpm is reasonable and matches the actual value. At this point, the red steel will neither pile up nor pull (piling and pulling refer to the tension between stands; a higher actual value than the set value will lead to piling up, and vice versa). Pulling is reflected in the finished product as a difference of approximately 2% in weight per meter between the head and the middle section. Since rebar is a bar, it can be approximated as a circular cross-section; a 2% difference in weight per meter means a 2% difference in cross-sectional area, and weight per meter equals cross-sectional area. Length (1m) density.

[0029] S3. Set the threshold for rapid descent value fluctuation.

[0030] Step S3 specifically involves the following: As the service life of the motor increases, the rigidity of the motor will decrease, and the actual speed drop value will increase. The increase in the actual speed drop value will directly affect whether the red steel can smoothly enter the rolling mill.

[0031] Calculate the absolute value A of the head-to-tail drop difference under different actual drop values ​​XL. Take a drop of length L from the head of the red steel and measure its weight M1. Take a drop of length L from the tail of the red steel and measure its weight M2. Then the absolute value A of the head-to-tail drop difference is A = |M1-M2| / M1. When A = 1%, the corresponding minimum actual drop value is XL1 and the maximum actual drop value is XL2. Then the drop value fluctuation threshold α = [XL1-XB, XL2-XB] and record the drop value fluctuation threshold α in the first calculation table.

[0032] In this embodiment, as Figure 3 The table shown is a table of the actual speed drop value XL and the measured absolute value A of the difference between the head and tail flow bars. In this table, the final difference between the head and tail flow bars is less than 1% as the criterion. The speed drop setting value and alarm value are also set to a standard of no more than 1%. The speed drop value fluctuation threshold α = ±3rpm can be obtained.

[0033] S4. Set the recovery cycle fluctuation threshold.

[0034] Step S4 is as follows: As the motor's usage cycle increases, the motor's start-up time and braking characteristics will decrease, which will increase the actual recovery cycle. An excessively long actual recovery cycle will cause a speed difference between the head and the middle material shape, resulting in a difference in the cross-section.

[0035] The actual recovery period TL and the measured absolute value A of the head and tail strip difference are calculated under different usage time conditions of the rolling mill. When A=1%, the actual recovery period is TL. Then the recovery period fluctuation threshold β=TL-TB and the recovery period fluctuation threshold β is recorded in the first calculation table.

[0036] In this embodiment, as Figure 4 The table shows the actual recovery cycle and the measured absolute value A of the head and tail runner difference under different motor usage conditions. Similarly, the runner difference of no more than 1% is used as the judgment standard and the selection standard for the expected value. It is estimated that it will exceed 1% at +20ms, so this value is set as the warning value.

[0037] S5. Set a motor characteristic discrimination mechanism based on the speed drop value fluctuation threshold and the recovery cycle fluctuation threshold.

[0038] Step S5 is as follows: For a rolling mill with a newly replaced motor, based on its rolling specifications, rolled steel grade, rolling mill stand, rolling mill incoming material temperature, and actual rolling mill speed, find the corresponding impact compensation value XB, speed drop value fluctuation threshold α, and recovery cycle fluctuation threshold β in the first calculation table. When the current actual speed drop value XL-XB > α, issue a motor rigidity abnormality alarm signal X0306; when the current actual recovery cycle TL-TB > β, issue a motor start-up time and braking characteristic abnormality alarm signal T0306.

[0039] The principle of the motor characteristic discrimination mechanism is as follows: like Figure 5 The diagram shown is a complete state diagram of a normal steel-gripping action, with time on the horizontal axis and rotational speed on the vertical axis.

[0040] When the stiffness of the motor decreases, the following will occur: Figure 6 As shown, the actual descent rate will increase, and the actual recovery period will also be prolonged.

[0041] When the motor stiffness is normal but the braking characteristics decrease, it will exhibit the following characteristics: Figure 7 The situation is as shown. The actual descent rate is normal, but the actual recovery period has increased.

[0042] Figure 5 , Figure 6 and Figure 7 These are all speed trend graphs under ideal conditions. Under normal circumstances, a certain range of fluctuations is allowed. Therefore, thresholds are set for speed drop value and recovery cycle to provide early warning of motor characteristic status.

[0043] This invention provides a method for determining the characteristics of a rolling mill motor, which enables the determination and control of the characteristics of the rolling mill motor, thereby predicting the real-time status of the rolling mill motor in advance. When the motor characteristics change beyond a safety threshold, an alarm is triggered in advance, thereby avoiding the failure of the preset impact compensation and reducing the probability of safety accidents.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for determining the characteristics of a rolling mill motor, characterized in that... Includes the following steps: S1. Determine the specifications, steel grade, process, and mill stand for rolling; The specific steps of step S1 are as follows: determining the rolling specifications, rolling steel grade, rolling mill stand number, rolling mill incoming material temperature T1, and actual rolling mill speed V0; S2. Accumulate the actual values ​​of speed drop and actual recovery cycles corresponding to different specifications, steel grades, and rolling speeds; The specific steps of step S2 are as follows: For a rolling mill stand, under the premise of different rolling specifications, rolling steel grades, and rolling mill incoming material temperature T1, a speed drop set value X is set, the actual speed drop value XL and the actual recovery cycle TL fed back by the motor sensor are recorded, and these data are used to establish the first calculation table. According to the data in the first calculation table, when the rolling specification, rolling steel grade, and mill stand number are fixed values, the actual descent value XL is related to the mill incoming material temperature T1, the actual recovery period TL is related to the actual descent value XL, and the matching degree between the descent set value X and the actual descent value XL is related to the rolling steel grade. Therefore, when the speed drop setting value X in the first calculation table is equal to the actual speed drop value XL, the speed drop setting value X at this time is used as the final impact compensation value XB, and the corresponding actual recovery period is TB. At this time, the red steel will neither pile up nor pull the steel. S3. Set the threshold for rapid descent value fluctuation; Specifically, step S3 is as follows: as the service life of the motor increases, the rigidity of the motor will decrease, and the actual value of the speed drop will increase. Calculate the absolute value A of the head-to-tail drop difference under different actual drop values ​​XL. Take a drop of length L from the head of the red steel and measure its weight M1. Take a drop of length L from the tail of the red steel and measure its weight M2. Then the absolute value A of the head-to-tail drop difference is A=|M1-M2| / M1. When A=1%, the minimum actual drop value is XL1 and the maximum actual drop value is XL2. Then the drop value fluctuation threshold α=[XL1-XB,XL2-XB] and record the drop value fluctuation threshold α in the first calculation table. S4. Set the recovery cycle fluctuation threshold; Specifically, step S4 involves the following: as the motor's usage cycle increases, the motor's start-up time and braking characteristics will decrease, thus increasing the actual recovery cycle. The actual recovery period TL and the measured absolute value A of the head and tail pass difference are calculated under different usage time conditions of the rolling mill. When A=1%, the actual recovery period is TL. Then the recovery period fluctuation threshold β=TL-TB and the recovery period fluctuation threshold β is recorded in the first calculation table. S5. Set a motor characteristic discrimination mechanism based on the speed drop value fluctuation threshold and the recovery cycle fluctuation threshold.

2. The method for determining the characteristics of a rolling mill motor according to claim 1, characterized in that: Step S5 specifically involves: for a newly replaced motor rolling mill, by using its rolling specifications, rolled steel grade, rolling mill stand, rolling mill incoming material temperature, and actual rolling mill speed, the corresponding impact compensation value XB, speed drop value fluctuation threshold α, and recovery cycle fluctuation threshold β in the first calculation table are searched. When the current actual speed drop value XL-XB > α, a motor rigidity abnormality alarm signal is issued; when the current actual recovery cycle TL-TB > β, a motor start-up time and braking characteristic abnormality alarm signal is issued.

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