Rear-end collision prevention control method for hot rolling coiler

Abstract

The invention relates to the technical field of hot rolling, in particular to a rear-end collision prevention control method for a hot rolling coiler, which comprises the following steps: S1, calculating the speed of a strip steel head when a finish rolling tail rack bites steel; s2, calculating the time for the head of the strip steel to reach a 1 # coiling machine; s3, calculating the minimum speed of the recoiling machine in real time to avoid rear-end collision or steel jamming accidents caused by untimely switching of the recoiling machine; and S4, limiting the speed of the recoiling machine by taking the minimum speed of the recoiling machine for avoiding the accidents of rear-end collision or steel blockage caused by untimely switching of the recoiling machine as the lower limit value of the tail speed of the previous strip steel recoiling machine. The method has the advantages that the head-to-tail interval of the two pieces of steel in front of the coiling machine is accurately calculated, and the given lower limit value of the coiling speed of the tail of the coiling machine is controlled, so that the head-to-tail interval time of the front and rear strip steel is kept longer than the switching time of the coiling machine, and the accident of steel blockage caused by rear-end collision of the strip steel in front of the coiling machine or incapability of switching the coiling machine in time can be effectively avoided; calculation is accurate, rolling rhythm is not affected, and application effect is good.

Description

Technical Field

[0001] The present invention relates to the technical field of hot rolling, and in particular to a hot rolling coiler anti-rear-end collision control method. Background Art

[0002] During the hot rolling mill's production process, after the strip is rolled into shape in the finishing mill, it needs to be coiled into coils by a coiler for subsequent transportation and handling. Typically, a hot rolling mill will have two or three coilers to perform this task. A central roller table and laminar flow cooling system are located between the finishing mill and the coiler to transport and cool the strip, ensuring it reaches the appropriate temperature and properties before coiling.

[0003] As the strip emerges from the finishing mill, a PLC (Programmable Logic Controller) program tracks and calculates the position of the strip's head and tail on the central roller table in real time to ensure smooth entry into the coiler and completion of the coiling operation. After the tail of the previous strip enters the coiler, the coiler must be switched. This involves opening and closing the coiler's valve and raising and lowering the pinch rolls, a process that typically takes several seconds.

[0004] When the rolling interval is large, the tail of the previous strip enters the coiler before the head of the next strip has emerged, or the time between the two strips entering the coiler is long enough. In this case, there will be no rear-end collision, and the coiler has ample time to complete the switching operation. However, as production continues to increase, the rolling rhythm gradually accelerates, and the interval between two strips becomes shorter and shorter. In this case, after the tail of the previous strip enters the coiler, the coiler may not have time to complete the switching operation, and the head of the next strip has already reached the coiler position, resulting in a steel jam. In more serious cases, the two strips in front and behind the rollers may even collide with each other, which not only affects production efficiency but also may damage the equipment, increase maintenance costs and safety risks. Summary of the Invention

[0005] The purpose of the present invention is to provide a hot rolling coiler anti-rear-end collision control method, which accurately calculates the time when the head of the next strip arrives at the coiler and the time when the tail of the previous strip enters the coiler in real time, and dynamically controls the lower limit of the coiler speed to control the minimum interval time between the two pieces of steel, giving the coiler sufficient switching time, preventing the occurrence of strip rear-end collision and steel jamming accidents, and improving production safety.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A hot rolling coiler anti-rear-end collision control method, comprising:

[0008] S1. Calculate the strip head speed when the finishing mill end stand bites the steel;

[0009] S2. Calculate the time when the strip head reaches the No. 1 coiler;

[0010] S3, real-time calculation of the minimum coiler speed to avoid rear-end collision or steel jamming caused by untimely coiler switching;

[0011] S4. The minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching is used as the lower limit of the speed of the tail of the coiler of the previous strip to limit the coiler speed.

[0012] In S1, the speed of the strip head when the finishing mill end stand bites the steel is calculated using the following formula:

[0013] v H =v0(1+f0)①

[0014] In formula ①, v0 represents the linear speed of the last effective stand of finishing rolling, in m / s; f0 represents the front slip rate of the last effective stand of finishing rolling, in %; v H It indicates the speed of the strip head when the finishing rolling last stand bites the steel, in m / s.

[0015] In S2, the time for the strip head to reach the No. 1 coiler is calculated using the following formula:

[0016]

[0017] In formula ②, a represents the acceleration rate of the strip head, in m / s 2 ; s0 represents the distance from the acceleration point to the 1# coiler, in m; s1 represents the distance from the last effective stand of the finishing rolling mill to the acceleration point, in m; t H Indicates the time when the strip head reaches the No. 1 coiler, in seconds.

[0018] In S3, the minimum coiler speed is calculated in real time to avoid rear-end collision or steel jamming caused by untimely coiler switching. The formula is as follows:

[0019]

[0020] In formula ③, t q Indicates the safe switching time of the coiler, in seconds; ds t Indicates the distance between the tail of the strip and the coiler, in s; dv L Indicates the minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching, in m / s.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By accurately calculating the head-to-tail interval between two pieces of steel in front of the coiler and controlling the lower limit of the coiling speed at the tail of the coiler, the head-to-tail interval between the front and rear strips can be kept greater than the coiler switching time. This can effectively avoid accidents such as strips colliding with each other in front of the coiler or steel jamming due to insufficient time to switch the coiler. The accurate calculation does not affect the rolling rhythm and has a good application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the anti-rear-end collision control process of the hot rolling coiler.

[0024] Figure 2 It is the speed curve of the coiler tail.

[0025] Figure 3 This is the principle diagram of the anti-rear-end collision control of the hot rolling coiler. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below 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.

[0027] The following examples are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0028] Example 1

[0029] At present, two control methods for preventing rear-end collision are commonly used in hot rolling production lines:

[0030] One is to limit the span of rolled products and control the steel feeding interval based on the experience of the finishing rolling operator;

[0031] Another method is to automatically control the steel feeding interval of the finishing mill by calculating and predicting the steel throwing and steel feeding time of the finishing mill to control the interval between the two pieces of steel to achieve the purpose of preventing rear-end collision.

[0032] Due to the variability of the coiling time and speed at the tail of the coiler, as well as the large errors inherent in speed prediction, the above two methods suffer from large calculation errors and are not very effective. Excessively large safety margins can affect the rolling rhythm, while too small a margin can make rear-end collisions impossible to avoid. The present invention provides a hot rolling coiler anti-rear-end collision control method that enables more precise control.

[0033] See Figure 1 ,See Figure 3 Taking the coiler of the hot rolling 1780 production line of a steel plant as an example, the previous strip is coiled by the 2# coiler, and the speed from coiling to the tail finish rolling is 10 meters per second. When there are 40 meters left at the tail of the previous strip, the next strip is finished rolled out. The hot rolling coiler anti-rear-end collision control method has the following specific steps:

[0034] Step 1: The final effective stand linear speed of the last strip of finishing rolling is 10m / s, and the final stand rolling slip rate is 10%. When the final stand of finishing rolling bites the steel, the strip head speed when the final stand of finishing rolling bites the steel is calculated according to the following formula:

[0035] v H =v0(1+f0)①

[0036] In formula ①, v0 represents the linear speed of the last effective stand of finishing rolling, in m / s; f0 represents the front slip rate of the last effective stand of finishing rolling, in %; v H Indicates the speed of the strip head when the finishing mill last stand bites the steel, in m / s;

[0037] According to formula ①, v H =10(1+10%)=11m / s.

[0038] Step 2: Taking the strip acceleration rate of 10% as an example, the distance from the last effective stand of the finishing rolling mill to the No. 1 coiler is 130 meters, and the distance from the last effective stand of the finishing rolling mill to the acceleration point is 20 meters. The time it takes for the strip head to reach the No. 1 coiler is calculated using the following formula:

[0039]

[0040] In formula ②, a represents the acceleration rate of the strip head, in m / s2, a=0.1 (given by the host computer according to the steel grade layer); s0 represents the distance from the acceleration point to the 1# coiler, s0=130-20=110, in m; s1 represents the distance from the last effective stand of the finishing rolling mill to the acceleration point, in m; t H Indicates the time when the strip head reaches the No. 1 coiler, in seconds;

[0041] According to formula ②,

[0042] Step 3: Take the coiler safety switching time as 7 seconds, and the coiling speed of 7 m / s when the tail of the upper strip is 40 m away from the 2# coiler. Calculate the minimum coiler speed in real time to avoid rear-end collision or steel jamming caused by untimely coiler switching using the following formula:

[0043]

[0044] In formula ③, t q Indicates the safe switching time of the coiler, in seconds; ds t Indicates the distance between the tail of the strip and the coiler, in m; dv L Indicates the minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching, in m / s;

[0045] According to formula ③,

[0046] Step 4: Calculate the speed dv l = 9.1m / s is used as the lower limit of the speed of the tail of the previous strip coiler to limit the speed of the 2# coiler coiling the strip tail, that is, the 2# coiler increases the speed from the current speed of 7m / s to 9.1m / s for coiling. Figure 2 Increase the running speed of the tail of the previous piece of steel to prevent rear-end collision and ensure safe switching of the two coilers.

[0047] Example 2

[0048] See Figure 1 Taking the coiler of the hot rolling 1780 production line of a steel plant as an example, the previous strip is coiled by the 2# coiler, and the speed from coiling to the tail finish rolling is 10 meters per second. When there are 25 meters left at the tail of the previous strip, the next strip is finished rolled out. The hot rolling coiler anti-rear-end collision control method has the following specific steps:

[0049] Step 1: The final effective stand linear speed of the last strip of finishing rolling is 10m / s, and the final stand rolling slip rate is 10%. When the final stand of finishing rolling bites the steel, the strip head speed when the final stand of finishing rolling bites the steel is calculated according to the following formula:

[0050] v H =v0(1+f0)①

[0051] In formula ①, v0 represents the linear speed of the last effective stand of finishing rolling, in m / s; f0 represents the front slip rate of the last effective stand of finishing rolling, in %; v H Indicates the speed of the strip head when the finishing mill last stand bites the steel, in m / s;

[0052] According to formula ①, v H =10(1+10%)=11m / s.

[0053] Step 2: Taking the strip acceleration rate of 10% as an example, the distance from the last effective stand of the finishing rolling mill to the No. 1 coiler is 130 meters, and the distance from the last effective stand of the finishing rolling mill to the acceleration point is 20 meters. The time it takes for the strip head to reach the No. 1 coiler is calculated using the following formula:

[0054]

[0055] In formula ②, a represents the acceleration rate of the strip head, in m / s2, a=0.1 (given by the host computer according to the steel grade layer); s0 represents the distance from the acceleration point to the 1# coiler, s0=130-20=110, in m; s1 represents the distance from the last effective stand of the finishing rolling mill to the acceleration point, in m; t HIndicates the time when the strip head reaches the No. 1 coiler, in seconds;

[0056] According to formula ②, we get:

[0057]

[0058] Step 3: Take the coiler safety switching time as 7 seconds, and the coiling speed of 7 m / s when the tail of the upper strip is 40 m away from the 2# coiler. Calculate the minimum coiler speed in real time to avoid rear-end collision or steel jamming caused by untimely coiler switching using the following formula:

[0059]

[0060] In formula ③, t q Indicates the safe switching time of the coiler, in seconds; ds t Indicates the distance between the tail of the strip and the coiler, in m; dv L Indicates the minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching, in m / s;

[0061] According to formula ③, we get:

[0062]

[0063] Step 4: Calculate the speed dv l =5.7m / s is used as the lower limit of the speed of the tail of the previous strip coiler to limit the speed of the 2# coiler coiling the strip tail, that is, when the 2# coiler decelerates from the current speed of 7m / s to 5.7m / s, it will no longer decelerate and maintain the coiling speed of 5.7 meters per second. Figure 2 The coiling is performed as shown in the curve of Example 2; the safe switching time of the two coilers is ensured.

[0064] See Figure 2 During normal production, the tail of the strip after finishing mill throws steel and runs at the throwing speed before the calculated deceleration point. After reaching the deceleration point, it is accelerated by 1m / s. 2 It decelerates at a fixed deceleration rate and drops to a creeping speed of 3m / s before entering the coiler. Tail positioning control is started before the strip enters the coiler, and it decelerates and stops after entering the coiler. When the anti-collision control is put into operation and it is calculated that the head of the next strip reaches the coiler too fast, in order to avoid the coiler not being able to switch in time, the tail of the previous strip does not slow down or even accelerates until it reaches the tail positioning control point in front of the coiler, and then the tail positioning operation is directly carried out, so as to widen the gap between the front and rear strips.

[0065] The present invention accurately calculates the head and tail interval of two pieces of steel in front of the coiler and controls the given lower limit value of the coiling speed at the tail of the coiler to keep the head and tail interval time of the front and rear strips greater than the coiler switching time. This can effectively avoid accidents such as the strips in front of the coiler colliding with each other or the coiler being too late to switch and cause steel jamming. The accurate calculation does not affect the rolling rhythm and the application effect is good.

Claims

1. A hot rolling coiler anti-rear-end collision control method, characterized in that: include: S1. Calculate the strip head speed when the finishing mill end stand bites the steel; S2. Calculate the time when the strip head reaches the No. 1 coiler; S3, real-time calculation of the minimum coiler speed to avoid rear-end collision or steel jamming caused by untimely coiler switching; S4. The minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching is used as the lower limit of the speed of the tail of the coiler of the previous strip to limit the coiler speed.

2. The anti-rear-end collision control method for a hot rolling coiler according to claim 1, characterized in that: In S1, the formula for calculating the strip head speed when the finishing rolling end stand bites the steel is as follows: v H =v0(1+f0)①In formula ①, v0 represents the linear speed of the last effective stand of finishing rolling, in m / s; f0 represents the front slip rate of the last effective stand of finishing rolling, in %; v H It indicates the speed of the strip head when the finishing rolling last stand bites the steel, in m / s.

3. The anti-rear-end collision control method for a hot rolling coiler according to claim 1, characterized in that: In S2, the time for calculating the strip head to reach the No. 1 coiler is calculated using the following formula: In formula ②, a represents the acceleration rate of the strip head, in m / s 2 ; s0 represents the distance from the acceleration point to the 1# coiler, in meters; s1 represents the distance from the last effective stand of the finishing rolling mill to the acceleration point, in meters; t H Indicates the time when the strip head reaches the No. 1 coiler, in seconds.

4. The anti-rear-end collision control method for a hot rolling coiler according to claim 1, characterized in that: In S3, the real-time calculation of the minimum coiler speed to avoid rear-end collision or coiler switching failure to cause steel jam is as follows: In formula ③, t q Indicates the safe switching time of the coiler, in seconds; ds t Indicates the distance between the tail of the strip and the coiler, in s; dv L Indicates the minimum speed of the coiler to avoid rear-end collision or steel jamming caused by untimely coiler switching, in m / s.

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