A method for stable coiling of thin strip steel

Abstract

A thin strip steel stable coiling method, comprising: step 1: judging whether the incoming material is a thin strip steel with a thickness of less than or equal to 0.3 mm; if yes, adopting a thin strip steel threading coiling mode in the coiler building stage, and setting the rotational speed increment of the coiler according to the thickness of the strip steel; step 2: after the strip steel is coiled about 0.5-1 turns on the coiler core shaft, the coiler control mode is switched to a torque control mode; step 3: in the process of the coiler torque rising to the target torque, a plurality of torque constant platforms are set; at the same time, different slopes alpha are set in different intervals before the set tension is reached, so as to further reduce the impact on the strip steel in the tension rising process; and step 4: when the absolute tension on the strip steel is still small, the strip steel tension between the turning pinch roll and the coiler is transmitted to a farther unit section to the coiler, so that the tension fluctuation of the strip steel is limited in a relatively small tension interval.

Description

Technical Field

[0001] This invention relates to the field of strip steel production processes in metallurgical technology, and particularly to a method for stable coiling of thin strip steel, wherein the strip steel coiling and threading control method is a method for stable coiling of thin strip steel. Background Technology

[0002] In the fast-paced continuous strip annealing production line, successful strip threading by the coiler plays a crucial role in strip production efficiency and product quality. Successful strip threading is a vital component of the strip production process. The threading control of the coiler at the exit section of the continuous cold-rolled annealing line is primarily achieved through the coordinated operation of equipment such as the steering pinch rolls, pressure rolls, conveyor belts, expandable mandrels, threading tables, and belt winding aids. Most cold-rolled lines at the exit section employ dual coilers (i.e., dual-channel) for strip coiling. For example, the main control methods for traditional dual coiler threading include... Figure 1 As shown:

[0003] The #1 steering pinch roller, the #1 winding machine, and the #1 guide plate complete the winding of the #1 channel; the #2 steering pinch roller, the #2 guide plate, and the #2 winding machine complete the winding of the #2 channel.

[0004] During production, the coiler feeds the strip steel, cut by the cross-cutting shear or roller shear, from the scissor position to the coiler at the feeding speed until the coiler winds up several turns. Before the coiler completes feeding, all pressure rollers and pinch rollers in the exit section are closed, and then the exit section drive equipment operates at the feeding speed. Once the strip steel reaches the coiler mandrel position and initial tension is established, the coiler switches from speed control to torque control to ensure the first few turns are tightly wound. After the coiler has wound up several turns, the belt winding aid opens, followed by the opening of the pressure rollers and pinch rollers, and then the exit section speed switches back to normal speed for normal winding.

[0005] However, the above technical solution has the following problem:

[0006] Under normal operating conditions, the automatic strip threading process can be completed well when the strip is thick. However, when producing thin strip, especially for certain steel grades with special material composition, the strip is brittle and thin, making it prone to transverse breakage during the winding and threading process. This not only causes the unit to stop and affects the production rhythm, but also results in the scrapping of products.

[0007] The main reasons for transverse fracture are as follows:

[0008] 1. Before the strip is transported to the coiler mandrel at the threading speed via the transmission equipment, it moves forward without tension. Then, during the tension building stage, due to the difference between the coiler speed and the threading speed, as well as the acceleration stage of the coiler speed during the subsequent tension increase process, the strip is subjected to uneven stress, which can easily cause the strip to tear.

[0009] 2. During the process of coiling assistance and opening of the turning pinch rolls, the instantaneous tension of the strip will fluctuate greatly due to the transmission of tension in the exit section. This process will also cause uneven lateral stress on the strip, which may lead to coiling tearing.

[0010] According to the online search conducted by the China and Foreign Patent Database Service Platform (www.cnipr.com), the invention "Method for Reducing Local Narrowing During Tension Building in Hot Continuous Rolling Coilers" with patent publication number "CN111633036A" is disclosed as follows:

[0011] A method for effectively reducing localized narrowing during the tension setting process of a hot strip coiler is disclosed. This method uses two tension settings—threading tension and coiling tension—to control the strip width. Specifically, threading tension is used during the initial coiling, and then gradually transitions to coiling tension until the tension gradually increases to the level of the coiling tension. The threading tension is less than or equal to the coiling tension. In other words, this method combines the advantages of both threading and coiling tension, organically integrating their strengths into a single solution, making it particularly suitable for the tension setting process of hot strip coilers.

[0012] However, the technical solution of this invention controls the strip width by combining two tension settings, threading tension and coiling tension, in order to reduce the local narrowing of the strip during the tensioning of the hot continuous rolling coiler. However, during the coiling tensioning stage, depending on the thickness of the material, the above technical solution cannot avoid strip tearing during the tensioning stage. Moreover, the tension on the strip is stabilized and the changes and fluctuations in tension are controlled, which makes the strip susceptible to large tension impacts and exacerbates tearing. Summary of the Invention

[0013] To overcome the above problems, the object of the present invention is:

[0014] To avoid strip tearing during the tension building stage, the strip tension is stabilized and its rate of change is controlled to prevent excessive tension impact that could cause tearing. Furthermore, by advancing the opening timing of the exit section's turning pinch rolls to the coiler control mode switch, the absolute value of strip tension fluctuations is reduced, further preventing tearing.

[0015] This technical solution's thin strip coiling and threading method involves setting different coiler speeds and exit threading speed differences based on the material thickness during the coiling and tension building stage to prevent strip tearing. During the torque increase process in the coiler's torque control mode, several constant torque plateaus are set, and different torque rise slopes are set between these plateaus. By stabilizing the tension on the strip and controlling the rate of tension change, large tension impacts that could cause tearing are avoided. Furthermore, by advancing the opening sequence of the exit section's turning pinch rolls to the coiler control mode switch, the absolute value of strip tension fluctuations is reduced, further preventing tearing.

[0016] The technical solution of this invention is as follows:

[0017] A method for stable winding of thin strip steel, characterized by comprising the following steps:

[0018] Step 1: Determine if the incoming material is a thin strip steel with a thickness ≤ 0.3mm. If the incoming material is a thin strip steel with a thickness ≤ 0.3mm, then during the coiler tensioning stage, after the strip head reaches the coiler mandrel, the coiler control mode will operate in speed control mode, using the thin strip steel threading and coiling mode.

[0019] When the coiler is in speed control mode, the percentage increase in the coiler's rotational speed is set differently depending on the thickness of the strip, with a setting range of 5%-20%. The thinner the strip, the smaller the speed increase of the coiler, in order to reduce the tension on the strip during the tensioning process.

[0020] Step 2: After the strip is wound on the coiler mandrel, the coiler control mode is switched to torque control mode.

[0021] Step 3: When the coiler control mode is switched to torque control mode, in order to avoid fluctuations in strip tension, in the initial stage of strip torque increase, all pressure rollers and steering pinch rollers in the exit section are raised. This allows the strip tension between the steering pinch rollers and the coiler to be transferred to the further unit section between the coiler while the absolute tension on the strip is still relatively small, thus limiting the strip tension fluctuation to a relatively small range.

[0022] Step 4: After switching to torque control mode, during the process of the winder torque increasing towards the target torque,

[0023] (1) Set a constant torque platform to reduce the impact on the strip during the tension increase process;

[0024] (2) At the same time, within different tension increase intervals before the calculated tension reaches the set tension, a slope α is set, that is, as the tension gradually increases, the tension increase acceleration is gradually reduced, further reducing the impact on the strip steel during the tension increase process.

[0025] According to the present invention, two constant torque platforms may be set between the three torque boosting stages, or one platform may be set between the two boosting stages.

[0026] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0027] In step 1: After the steel strip reaches the mandrel of the coiler, it bites into the mandrel under the action of the winding aid belt. At this time, the coiler is operating in speed control mode, and its speed setting value is:

[0028] v1 = v(1 + k)

[0029] Where v1 is the linear speed of the winding machine (unit: meters / minute), controlled by the variable frequency motor of the winding machine, and v is the tape threading speed of the unit (unit: meters / minute).

[0030] The percentage of rotational speed increment k ranges from 0.05 to 0.2. The thinner the strip, the smaller the value of k.

[0031] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0032] Step 2: After the strip is wound on the coiler mandrel for about 0.5-1 turns, the coiler control mode is switched to torque control mode.

[0033] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0034] In step 3, when the coiler control mode is switched to torque control mode, all pressure rollers and pinch rollers are raised, and the strip tension between the steering pinch roller and the coiler is transferred to the further unit section between the coiler and the coiler, so that the strip tension fluctuation is limited to a relatively small tension range.

[0035] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0036] In step 3, when the coiler control mode is switched to torque control mode, all pressure rollers and pinch rollers are raised, transferring the strip tension between the steering pinch rollers and the coiler to a more distant section between the coiler and the unit, thus limiting the strip tension fluctuation to 10-20 N / mm. 2 The range.

[0037] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0038] After step 3, proceed to step 4:

[0039] When switching to torque control mode, the basic automated control system (L1) will calculate and output the torque of the winding machine according to the set tension target value. The torque at the moment of switching to torque control mode will be increased by a slope of α until the tension calculated based on the torque reaches the target tension.

[0040] Each product is different, and its target tension is different.

[0041] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0042] In step 4, two constant torque plateaus are set according to different torque increase ratios and maintained for a certain period of time to reduce the impact on the strip during the tension increase process.

[0043] Before reaching the target tension, different slopes α are set during the torque increase phase between each constant torque plateau. That is, as the tension gradually increases, the tension increase acceleration is gradually reduced to further reduce the impact on the strip during the tension increase process.

[0044] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0045] A constant torque plateau is set at 50% and 75% of the torque increase compared to the initial torque, with each plateau lasting 0.5s, to reduce the impact on the strip during the tension increase process.

[0046] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0047] In the three torque boosting stages between the two constant torque plateaus, different slopes α are set as follows:

[0048] From the initial torque to the constant speed plateau 1, the torque increase slope α1 is 0.4-0.5.

[0049] The torque increase slope α2 between constant speed plateau 1 and constant speed plateau 2 is 0.3-0.35.

[0050] After the constant torque plateau 2 ends, the torque is increased to the target torque with a slope of α3 = 0.2-0.25.

[0051] That is, as the tension gradually increases, the tension-increasing acceleration is gradually reduced to further reduce the impact on the strip during the tension increase process. Afterwards, the exit section speed is increased to normal speed for normal winding.

[0052] According to the present invention, a method for stable winding of thin strip steel is characterized in that:

[0053] In the three torque boosting stages between the two constant torque plateaus, different slopes α are set as follows:

[0054] From the initial torque to the constant speed plateau 1, the torque increase slope α1 is 0.5.

[0055] The torque increase slope α2 between constant speed plateau 1 and constant speed plateau 2 is 0.35.

[0056] After the constant torque plateau 2 ends, the torque is increased to the target torque with a slope of α3=0.2. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the original strip winding and coiling process, which is mostly carried out by a double coiler (i.e., dual-channel) at the exit section of the cold rolling processing line.

[0058] Figure 2 This is a schematic diagram showing the changes in the winding machine torque and calculated tension.

[0059] Figure 3 This is a schematic diagram showing the changes in winding machine torque and calculated tension during the threading and winding process of this invention. Detailed Implementation

[0060] Figure 2 In the diagram, X1 represents the moment when the coiler switches from speed control to torque control mode, which is also the moment when the steering pinch roll opens; Y1 represents the calculated torque at the moment when the coiler switches from speed control to torque control mode; Y2 represents the target torque calculated based on the set tension; 1 is a schematic line illustrating the change in coiler torque; and 2 is a schematic line illustrating the change in theoretical tension of the strip.

[0061] Figure 3 In the diagram, X1 represents the moment when the coiler switches from speed control to torque control mode, which is also the moment the steering pinch roll opens. Y1 represents the calculated torque at the moment the coiler switches from speed control to torque control mode. Y2 represents the target torque calculated based on the set tension. 1 is a schematic line illustrating the change in coiler torque, and 2 is a schematic line illustrating the change in theoretical tension on the strip. 3 represents torque boosting segment 1 with a slope of α1, 4 represents torque boosting segment 2 with a slope of α2, 5 represents torque boosting segment 3 with a slope of α3, where α1 > α2 > α3. 6 represents torque constant plateau segment 1, and 6 represents torque constant plateau segment 2.

[0062] The speed setting of the coiler during the strip tensioning stage and the constant torque platform during the torque boosting stage, as well as the torque boosting slope, are all set by parameters given by the electrical control program of the basic process control system of the production line, and are achieved by controlling the output current of the main motor of the coiler.

[0063] This invention addresses the problem of strip breakage during the coiling and threading process at the exit section of a continuous annealing line for producing thin strip steel. By setting different coiling speed differences during the strip tension building stage and setting a constant tension platform and different torque rise slopes during the torque boosting stage, the tension stability of the strip during the threading and coiling process is improved. By setting the action of the deflecting pinch rollers at the stage when the strip is under low tension, strip breakage caused by tension fluctuations is avoided, greatly improving the production stability of the continuous annealing unit and reducing the scrap rate.

[0064] Example

[0065] The following analysis uses the automatic threading process of the No. 2 winding machine at the outlet of a company's continuous annealing production line to illustrate the control effect after the application of this technical solution. Meanwhile, the No. 1 winding machine still operates in the original threading and winding mode.

[0066] The unit produces a 0.265mm thick strip steel with an exit threading speed of 30m / min. After the strip head reaches the coiler mandrel, it bites into the mandrel under the action of the winding aid belt. At this time, the coiler control mode operates in speed control mode, with a speed setpoint of v1 = v(1 + k). Here, v1 is the coiler linear speed, controlled by the coiler's variable frequency motor, and v is the unit's threading speed of 30m / min. For a 0.265mm thick strip steel, k is taken as 0.15, resulting in a calculated v1 = 34.5m / min. After the strip steel has been wound approximately 0.5 turns on the coiler mandrel, the coiler control mode switches to torque control mode. At this time, all pressure rollers and pinch rollers are raised, transferring the strip tension between the deflecting pinch rollers and the coiler to the further unit section between the coiler and the coiler, thus limiting the strip tension fluctuation to a relatively small range. Subsequently, the basic automated control system (L1) continuously calculates and outputs the coiler's torque based on the set tension target value. Two constant torque plateaus are set at points where the torque has increased by 50% and 75% compared to the initial torque, with each plateau lasting 0.5 seconds, to reduce the impact on the strip during tension increase. Different slopes α are set for the three torque increase stages between the two constant torque plateaus. The slope α1 for the torque increase from the initial torque to the constant speed plateau 1 is 0.5.

[0067] The torque increase slope between constant speed platform 1 and constant speed platform 2 is α2 = 0.35. After constant torque platform 2, the torque is increased to the target torque with a slope of α3 = 0.2. That is, as the tension gradually increases, the tension increase acceleration is gradually reduced, further reducing the impact on the strip during the tension increase process. Afterwards, the exit section speed is increased to constant speed for normal speed winding.

[0068] Through on-site comparative practice, when using the original control system to thread the No. 1 coiler, almost 100% of the strips broke during threading when the strip thickness was below 0.3mm; however, after adopting the new control method during the threading process of the No. 2 coiler, the automatic threading function without strip breakage was completed 100%.

[0069] This invention can be widely used in continuous annealing production lines for producing thin strip steel and has high application value.

Claims

1. A method for stable winding of thin strip steel, characterized in that, Includes the following steps: Step 1: Determine if the incoming material is a thin strip steel with a thickness ≤ 0.3mm. If the incoming material is a thin strip steel with a thickness ≤ 0.3mm, then during the coiler tensioning stage, after the strip head reaches the coiler mandrel, the coiler control mode will operate in speed control mode, using the thin strip steel threading and coiling mode. When the coiler is in speed control mode, the percentage increase in the coiler's rotational speed is set differently depending on the thickness of the strip, with a setting range of 5%-20%. Step 2: After the strip is wound on the coiler mandrel, the coiler control mode is switched to torque control mode; Step 3: When switching the coiler control mode to torque control mode, in the initial stage of the coiler torque increase, all pressure rollers and deflecting pinch rollers in the exit section are raised to limit the tension fluctuation of the strip to 10-20 N / mm. 2 The interval; Step 4: After switching to torque control mode, during the process of the winder torque increasing towards the target torque, (1) Set a constant torque platform; (2) At the same time, within different tension increase intervals before the calculated tension reaches the set tension, the winding machine torque increase slope α is set, that is, as the tension gradually increases, the tension increase acceleration is gradually reduced.

2. The method for stable winding of thin strip steel according to claim 1, characterized in that: In step 1: After the steel strip reaches the mandrel of the coiler, it bites into the mandrel under the action of the winding aid belt. At this time, the coiler is operating in speed control mode, and its speed setting value is: v1 = v(1 + k) Where v1 is the linear speed of the winding machine, in meters per minute, controlled by the winding machine's variable frequency motor; v is the tape-feeding speed of the unit, in meters per minute; and k is the percentage coefficient for the rotational speed increment. The percentage coefficient k for the rotational speed increment is 0.05-0.

2. The thinner the strip, the smaller the value of k.

3. The method for stable winding of thin strip steel according to claim 1, characterized in that: Step 2: After the strip is wound 0.5-1 turns on the coiler mandrel, the coiler control mode is switched to torque control mode.

4. The method for stable winding of thin strip steel according to claim 1, characterized in that: In step 4, two constant torque plateaus are set according to different torque boost ratios and maintained for a certain period of time. Before reaching the target tension, different slopes α are set during the torque increase phase between each constant torque platform. That is, as the tension gradually increases, the tension increase acceleration is gradually reduced.

5. The method for stable winding of thin strip steel according to claim 4, characterized in that: A constant torque plateau is set at 50% and 75% of the torque increase compared to the initial torque, with each plateau lasting 0.5 seconds.

6. The method for stable winding of thin strip steel according to claim 5, characterized in that: The following sets different slopes α for the three torque-boosting stages consisting of two constant torque plateaus: From the initial torque to the constant speed plateau 1, the torque increase slope α1 is 0.4-0.

5. The torque increase slope α2 between constant speed plateau 1 and constant speed plateau 2 is 0.3-0.

35. After the constant torque plateau 2 ends, the torque is increased to the target torque with a slope of α3 = 0.2-0.

25. That is, as the tension gradually increases, the acceleration of the tension increase is gradually reduced. Then, the speed of the exit section is increased to the normal speed state, and normal speed winding is performed.

7. The method for stable winding of thin strip steel according to claim 6, characterized in that: Different slopes α are set for the three torque boosting stages as follows: From the initial torque to the constant speed plateau 1, the torque increase slope α1 is 0.

5. The torque increase slope α2 between constant speed plateau 1 and constant speed plateau 2 is 0.

35. After the constant torque plateau 2 ends, the torque is increased to the target torque with a slope of α3=0.2.

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