Method for controlling the non-pressed length of a billet head and method for pressing a continuous casting billet

Abstract

The application provides a method for controlling the non-pressing length of a billet head and a pressing method of a continuous casting billet, and belongs to the technical field of continuous casting, and comprises the following steps: setting a calibration non-pressing interval and a process non-pressing interval at the billet head of the continuous casting billet; during the process of drawing the billet, when the rear end of the calibration non-pressing interval reaches the position of the press-down section of the puller-straightener in sequence along the drawing direction, the puller-straightener at the corresponding position is calibrated gradually in sequence; when the rear end of the process non-pressing interval passes through the puller-straightener which is calibrated gradually, the puller-straightener at the corresponding position which is calibrated gradually is made to perform pressing down, so that the non-pressing length of the billet head is located in the process non-pressing interval. By using the application, the problem that there is no effective solution to effectively control the non-pressing length of the billet head, reduce the cost of recycling the non-pressing billet and avoid the influence of the failure of calibration of the puller-straightener on the pressing process in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of continuous casting technology, and more specifically, to a method for controlling the non-reduction length of the billet head and a method for reducing the continuous casting billet. Background Technology

[0002] From a technological perspective, the reduction technique has a significant effect on improving the internal quality of continuously cast billets, and it is now widely used in various billet types. However, in terms of control and execution, during the initial casting process of each continuous casting cycle, the billet head is relatively hard and cannot be reduced. Furthermore, the control of the reduction initiation is jointly controlled by primary and secondary levels, resulting in a long section of the billet head that cannot be reduced. Steel grades that require reduction to improve their internal quality are often high-grade specialty steels and other special steels. Billets that are not reduced must be recycled, leading to billet waste and reduced yield and profit.

[0003] In existing methods for controlling the pressing process, offline calibration has been largely phased out due to its high workload and the inability to guarantee pressing accuracy. Currently, online automatic calibration is generally used. To ensure operational safety, during the initial casting process, after the billet head has been removed and all straightening machines have billets underneath, the primary operator triggers the calibration process. The program simultaneously calibrates all straightening machines, maximizing efficiency. If any straightening machine fails to calibrate, the pressing process is halted, and on-site personnel investigate the cause of the calibration failure. If calibration is successful, the pressing process begins, with the secondary operator issuing the pressing amount to initiate the pressing.

[0004] In the existing methods described above, due to the low casting speed during the initial pouring process, the billet located below the leveling machine may not be ready for pressing. Even if pressing is possible, the process may not issue the pressing amount, and the billet will remain unpressed. Unpressed billets need to be remelted, and if they are not cut, it will affect the rolling process. Extensive field statistics show that, using the existing methods, the unpressed billet length during the initial pouring process is generally over 10m. Sometimes, due to factors such as delays in manual operation and slow increases in casting speed, the unpressed billet length can reach over 20m. For large billets, such as 250×300mm cross-section billets, this waste is significant. Furthermore, these unpressed billets need to be remelted, increasing costs. The larger the cross-section, the greater the impact, which can even become unacceptable.

[0005] In summary, there is currently a lack of effective solutions in the existing technology to control the length of the billet without pressing down, so as to reduce the cost of remelting the billet without pressing down and to prevent the pressing process from being affected by the failure of the straightening machine calibration. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide a method for controlling the length of the billet head that is not pressed down and a method for pressing down the continuously cast billet, so as to solve the problem in the prior art that there is no effective solution to control the length of the billet head that is not pressed down, so as to reduce the cost of returning the billet head to the furnace and to prevent the pressing process from being affected by the failure of the straightening machine calibration.

[0007] This invention provides a method for controlling the non-pressing length of the billet head, comprising the following steps:

[0008] A calibration non-reduction zone and a process non-reduction zone are set at the billet head of the continuously cast billet; wherein, the length of the process non-reduction zone is greater than the length of the calibration non-reduction zone;

[0009] During the drawing process, along the drawing direction, when the rear end of the calibrated non-pressing section reaches the position of the straightening machine in the pressing section in sequence, the straightening machines at the corresponding positions are gradually calibrated in sequence;

[0010] When the rear end of the non-pressurized section of the process passes the gradually calibrated tension leveler, the tension leveler at the corresponding position performs pressing down to control the non-pressurized length of the billet to be within the non-pressurized section of the process.

[0011] Furthermore, in a preferred embodiment, the method further includes:

[0012] In the billet head region where the drawing speed is lower than normal, a low solidification end reduction process is added to the preset two-stage reduction process table so that when the rear end of the non-reduction section passes the first tension leveler of the reduction section, the low solidification end reduction process causes the first tension leveler of the gradual calibration to perform reduction; wherein, the length of the low solidification end is less than the preset process solidification end in the two-stage reduction process table.

[0013] Furthermore, a preferred approach is to add a reduction process with a low solidification end to the preset two-stage reduction process table.

[0014] The pressing process for the low solidification end is set to a single-roller pressing process.

[0015] Furthermore, in a preferred embodiment, the method further includes:

[0016] The length of the cast billet produced during the low casting speed period during the initial casting process is recorded as the questionable length, and the cast billet with the questionable length is marked as a quality questionable cast billet; wherein, the casting speed of the cast billet during the low casting speed period is less than the preset critical casting speed; the critical casting speed is less than the normal casting speed.

[0017] Furthermore, a preferred approach is to calculate the length of the cast billet generated during the low-speed casting period in the process of tracking and recording the length of the cast billet generated during the low-speed casting period using the following formula:

[0018] L t =V·Δt

[0019] L = L pre +L t ;

[0020] Among them, L t V is the length of the billet within the cycle; V is the casting speed within the cycle; Δt is the cycle time; L is the length of the billet produced during the cumulative low casting speed period; L pre The length of the billet produced during the low casting speed period before the current moment.

[0021] Furthermore, in a preferred embodiment, the method further includes:

[0022] The length of the billet with questionable quality is reduced by the length of the billet within the non-pressurization range of the process, and the billet is then classified as a quality-downgraded billet.

[0023] In addition, a preferred approach is to set the calibration non-pressurization range according to actual process requirements.

[0024] Furthermore, a preferred approach is to set the non-pressurization range of the process according to actual process requirements.

[0025] Furthermore, a preferred embodiment is that the length of the calibration non-pressurization interval is 1.5m; and the length of the process non-pressurization interval is 2.0m.

[0026] The present invention also provides a method for pressing down a continuously cast billet, characterized in that, during the pressing down process of the continuously cast billet, the non-pressing length of the billet head is controlled by the method described above for controlling the non-pressing length of the billet head.

[0027] As can be seen from the above technical solution, the method for controlling the non-pressurization length of the billet head and the pressing method for continuous casting billets provided by the present invention, by setting a calibrated non-pressurization interval and a process non-pressurization interval at the billet head of the continuous casting billet, and ensuring that the length of the process non-pressurization interval is greater than the length of the calibrated non-pressurization interval, then, during the billet drawing process, along the billet drawing direction, when the rear end of the calibrated non-pressurization interval sequentially reaches the position of the straightening machine in the pressing section, the straightening machines at the corresponding positions are sequentially calibrated. Then, when the rear end of the process non-pressurization interval passes the sequentially calibrated straightening machines, the sequentially calibrated straightening machines at the corresponding positions are pressed down, thereby controlling the non-pressurization length of the billet head. By controlling the non-pressurization range of the process, the gradual calibration of the straightening machine and the instant pressing of the billet head can be achieved. Compared with the existing technology of simultaneous calibration and rectification of all straightening machines and pressing process, the non-pressurization range of the billet head can be controlled within the set process non-pressurization range, thereby reducing the limit of the non-pressurization range of the billet head during the casting process and reducing the cost of scrap billet return to the furnace. Moreover, the gradual calibration method adopted means that even if a straightening machine fails to be calibrated (marked as calibration failure), the calibration of subsequent straightening machines can continue. In the subsequent pressing process, as long as the straightening machine that failed to be calibrated is not used, no action is required, thereby minimizing the impact of calibration failure on pressing.

[0028] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0029] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings, and with a more complete understanding of the invention.

[0030] Figure 1 A flowchart of a method for controlling the non-pressed length of the billet head according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the position and calibration of the tension leveling machine according to Comparative Example 1 of the present invention;

[0032] Figure 3 This is a schematic diagram of the gradual calibration of the tension leveling machine according to Embodiment 1 of the present invention;

[0033] Figure 4 This is a graph showing the trend of casting speed change during the start-up process of a continuous casting machine according to Embodiment 1 of the present invention;

[0034] Figure 5This is a comparison diagram of the billet casting intervals during the calibration non-pressurization interval, the process non-pressurization interval, and the low casting speed period after the start of casting, according to Embodiment 1 of the present invention. Detailed Implementation

[0035] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details.

[0036] In response to the problem that the existing technologies mentioned above lack an effective solution to control the length of the billet without pressing down, so as to reduce the cost of returning the billet without pressing down and to prevent the pressing process from being affected by the failure of the straightening machine calibration, a method for controlling the length of the billet without pressing down and a pressing method for continuously cast billets are proposed.

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] To illustrate the method for controlling the non-reduction length of the billet head and the method for reducing the length of the continuously cast billet provided by the present invention, Figure 1 A flowchart of a method for controlling the non-pressed length of the billet head according to an embodiment of the present invention is shown; Figure 2 The position and calibration of the tension leveler according to Comparative Example 1 of the present invention are shown; Figure 3 The stepwise calibration of the tension straightener according to Embodiment 1 of the present invention is shown; Figure 4 The trend of casting speed variation during the start-up process of a continuous casting machine according to Embodiment 1 of the present invention is shown; Figure 5 A comparison of the billet casting intervals during the calibration non-pressurization interval, the process non-pressurization interval, and the low casting speed period after the start of casting is shown according to Embodiment 1 of the present invention.

[0039] like Figure 1 As shown, the method for controlling the non-pressing length of the billet head provided by the present invention includes the following steps:

[0040] Step S1: Set the calibration non-reduction interval and the process non-reduction interval at the billet head of the continuously cast billet; wherein, the length of the process non-reduction interval is greater than the length of the calibration non-reduction interval.

[0041] Specifically, a calibration non-pressurization zone and a process non-pressurization zone are set at the billet head of the continuously cast billet. One end of both the calibration non-pressurization zone and the process non-pressurization zone is the front end of the billet head. Since the length of the process non-pressurization zone is greater than the length of the calibration non-pressurization zone, the rear end of the process non-pressurization zone is located behind the calibration non-pressurization zone. That is, along the casting direction, the rear end of the calibration non-pressurization zone passes through the straightening machine first, and the rear end of the process non-pressurization zone passes through the straightening machine later. The calibration non-pressurization zone and the process non-pressurization zone are calibrated on the continuously cast billet. In this invention, the billet head refers to the section of the billet before the start of casting. The length of the billet head is determined by the actual process or steel grade.

[0042] As a preferred embodiment of the present invention, the calibration non-pressurization range is set according to actual process requirements.

[0043] As a preferred embodiment of the present invention, the non-pressure range of the process is set according to the actual process requirements.

[0044] Specifically, the calibration non-pressing interval and the process non-pressing interval in the technical solution of this invention are both set according to actual process requirements, and are generally set by process engineers. The length of the process non-pressing interval is greater than the length of the calibration non-pressing interval to ensure that the tension leveling machine performs the pressing operation only after calibration is completed.

[0045] As a preferred embodiment of the present invention, the length of the calibration non-pressurization interval is 1.5m; the length of the process non-pressurization interval is 2.0m.

[0046] It should be noted that: the length of the calibration non-pressurization interval is 1.5m; the length of the process non-pressurization interval is 2.0m, which is a preferred embodiment of the present invention, but can be set by the process personnel as needed.

[0047] Step S2: During the drawing process, along the drawing direction, when the rear end of the calibrated non-pressing section reaches the position of the straightening machine in the pressing section in sequence, the straightening machines at the corresponding positions are gradually calibrated.

[0048] Specifically, during the billet pulling process, the billet in the non-pressurized section moves forward along the pulling direction. Through program tracking, the straightening machine that the rear end of the non-pressurized section passes through can be identified. As the rear end of the non-pressurized section sequentially reaches the straightening machine position in the pressing section, the straightening machines at the corresponding positions are calibrated sequentially. Here, the calibration of the straightening machine in this invention refers to the calibration of the roll gap of the straightening machine. In the prior art, the calibration of the straightening machine is a prerequisite for subsequent pressing operations by the straightening machine; this is prior art, and this invention does not specifically limit it.

[0049] Step S3: When the rear end of the non-pressurized section of the process passes the gradually calibrated tension leveler, the tension leveler at the corresponding position is pressed down to control the non-pressurized length of the billet head to be within the non-pressurized section of the process.

[0050] Specifically, the billet in the non-pressurized zone moves forward along the casting direction during the casting process. Through program tracking, it can be known that the rear end of the non-pressurized zone passes through the gradually calibrated straightening machine. When the rear end of the non-pressurized zone passes through the gradually calibrated straightening machine, the corresponding gradually calibrated straightening machine performs pressing down to control the non-pressurized length of the billet head to be within the non-pressurized zone.

[0051] For example, when the rear end of the billet in the non-pressurized zone passes the first straightening machine, the first straightening machine immediately performs calibration. After the first straightening machine completes calibration, and the rear end of the non-pressurized zone passes the first straightening machine, the first straightening machine immediately presses down, thus completing the gradual calibration and immediate pressing of all straightening machines. If one straightening machine fails to calibrate, it is marked as a calibration failure, and the calibration of subsequent straightening machines continues. During the subsequent pressing process, as long as the straightening machine that failed calibration is not used, no action is taken, thereby minimizing the impact of calibration failure on pressing.

[0052] As a preferred embodiment of the present invention, the method for controlling the non-pressing length of the billet head further includes:

[0053] In the billet head region where the drawing speed is lower than normal, a low solidification end reduction process is added to the preset secondary reduction process table so that when the rear end of the non-reduction section passes the first gradually calibrated straightening machine in the reduction section, the low solidification end reduction process causes the first gradually calibrated straightening machine to perform the reduction; wherein, the length of the low solidification end is less than the preset process solidification end in the secondary reduction process table.

[0054] Specifically, for the billet produced in the billet head area, the casting speed is low and the solidification end is relatively early, which does not meet the requirements of the normal reduction range and cannot complete the normal reduction. By adding the reduction process corresponding to the low solidification end in the secondary reduction process table, the process reduction amount can be achieved immediately after the process does not reduce the range, thus truly achieving real-time reduction.

[0055] As a preferred embodiment of the present invention, in the process of adding a low solidification end reduction process to the preset two-stage reduction process table,

[0056] The pressing process for the low solidification end is set to a single-roll pressing process.

[0057] As a preferred embodiment of the present invention, the method for controlling the non-pressing length of the billet head further includes:

[0058] The length of the cast billet produced during the low casting speed period during the initial casting process is recorded as the questionable length, and the cast billet with the questionable length is marked as a quality questionable cast billet; wherein, the casting speed of the cast billet during the low casting speed period is less than the preset critical casting speed; the critical casting speed is less than the normal casting speed.

[0059] Specifically, the preset critical casting speed refers to the speed at which, even if the billet is pressed down, the quality of the billet cannot be guaranteed. The preset critical casting speed can be determined through experiments and the pressing process. In this invention, the length of the billet produced during the low casting speed period, i.e., the low casting speed billet range after the start of casting, is used to record abnormal billets, i.e., billets with questionable quality. Even if they are pressed down immediately, the quality still cannot be guaranteed. However, this does not affect the subsequent steel rolling process, and the quality still needs to be assessed through billet separation.

[0060] As a preferred embodiment of the present invention, in the process of tracking and recording the length of the cast billet generated during the low casting speed period in the initial casting process, the length of the cast billet generated during the low casting speed period is calculated using the following formula:

[0061] L t =V·Δt

[0062] L = L pre +L t ;

[0063] Among them, L t V is the length of the billet within the cycle; V is the casting speed within the cycle; Δt is the cycle time; L is the length of the billet produced during the cumulative low casting speed period; L pre The length of the billet produced during the low casting speed period before the current moment.

[0064] Specifically, in the process of tracking and recording the length of the cast billet generated during the low casting speed period during the initial casting process, the length of the cast billet generated during the low casting speed period can be accumulated by setting a cycle time, such as 3s, 4s, 5s, etc.

[0065] As a preferred embodiment of the present invention, the method for controlling the non-pressing length of the billet head further includes:

[0066] The length of the billet with questionable quality is removed from the section where the process does not press down, and the billet is then classified as a quality-downgraded billet.

[0067] The continuous casting billet reduction method provided by the present invention controls the non-reduction length of the billet head by means of the method described above for controlling the non-reduction length of the billet head during the continuous casting billet reduction process.

[0068] By setting a calibrated non-reduction zone and a process non-reduction zone at the billet head of the continuously cast billet, and ensuring that the length of the process non-reduction zone is greater than the length of the calibrated non-reduction zone, during the billet drawing process, along the drawing direction, as the rear end of the calibrated non-reduction zone sequentially reaches the position of the straightening machine in the reduction section, the straightening machines at the corresponding positions are gradually calibrated. Then, when the rear end of the process non-reduction zone passes the gradually calibrated straightening machines, the corresponding gradually calibrated straightening machines are pressed down to control the non-reduction length of the billet head within the process non-reduction zone, thereby achieving gradual calibration of the straightening machines. The calibration and immediate pressing of the billet head, compared to the pressing process after simultaneous calibration and rectification of all straightening machines in the existing technology, can control the non-pressurization range of the billet head within the set process non-pressurization range, thereby minimizing the non-pressurization range of the billet head during the initial casting process and reducing the cost of scrap billets being recycled. Furthermore, the gradual calibration method adopted means that even if a straightening machine fails to calibrate (marked as calibration failure), subsequent straightening machines can continue to be calibrated. In the subsequent pressing process, as long as the straightening machine that failed to calibrate is not used, no action is required, thus minimizing the impact of calibration failure on pressing.

[0069] To better illustrate the method for controlling the non-reduction length of the billet head and the reduction method for continuously cast billets provided by this invention, the following examples are given:

[0070] Comparative Example 1

[0071] Taking a 250x300mm large billet casting machine in a steel plant as an example, the main steel grade produced by this casting machine is bearing steel GCr15. It has 6 straightening machines, arranged as follows: Figure 2 As shown in the current original program logic, the straightening machines are calibrated only after the billet head has passed the last straightening machine and completed billet removal and traveled a certain distance. This calibration is initiated by the operator. This ensures that all straightening machines have hot billets underneath, and the calibration is performed simultaneously on all six straightening machines, resulting in high efficiency. However, even if pressing is immediately executed after calibration, for example starting from roll #2, a long section of billet from roll #2 to the front of the billet head remains unpressed. Field feedback indicates that operators typically leave 10-16 meters of billet unpressed during the control process. Over long-term production, this leads to a large accumulation of scrap billets, significantly increasing costs.

[0072] Example 1

[0073] The method for controlling the length of the billet head that is not pressed down, provided by the present invention, is applied to a steel plant in Comparative Example 1. Taking a large square billet casting machine of 250X300mm as an example, the main steel grade produced by the casting machine is bearing steel GCr15, and there are 6 straightening machines.

[0074] The calibration non-pressure range is set to 1.5m, and the process non-pressure range is set to 2.0m. Figure 3As shown, when the billet reaches a certain position and the first straightening machine is just outside the calibrated non-pressurization range, the first straightening machine is immediately automatically calibrated, without waiting until... Figure 2 After the billet head passes the last straightening machine and is removed, the same logic applies: the billet head keeps moving forward until it reaches the second straightening machine. When it is just outside the calibration non-pressurization range, the second straightening machine is automatically calibrated. This process is repeated to complete the gradual calibration of all straightening machines.

[0075] As designed, because the length of the non-pressing section in the process (2.0m) is greater than the calibration non-pressing section length (1.5m), the first straightening machine cannot be pressed down immediately after calibration. This is a safety time specifically allocated for the straightening machine calibration process. Figure 3 Following the same logic, when the first straightening machine is located just outside the non-pressurization range of the process, it can execute the pressing process. If the following processes are already in place, the straightening machine will execute them immediately, thus limiting the non-pressurization length to only 2.0m. This process continues, with gradual calibration and instantaneous pressing being executed gradually, ultimately achieving both gradual calibration and instantaneous pressing during the pouring process.

[0076] Because the initial casting process typically involves a speed-up phase, the billet temperature is relatively low during the low-speed phase, and the solidification process at the end is also a gradual increase. Figure 2 In the normal process, the solidification end can only be normally pressed down after it is greater than 17.0m. At this time, when the first tension leveler is just outside the non-pressurization range of the process, the solidification end must be before the first tension leveler, so it cannot be pressed down immediately, which will increase the non-pressurization range.

[0077] In order to enable the pressing process immediately when the first straightening machine is just outside the non-pressing range of the process, a specific processing method is adopted. The program is set to perform a single roll pressing of 15mm when the solidification end is greater than 8m. When the solidification is greater than the normal process solidification end, it directly switches to the normal pressing process. This can ensure that the non-pressing range of the billet head is as short as possible and ensure the smooth operation of the subsequent steel rolling process.

[0078] At this point, in order to ensure as much pressing as possible, but due to the low casting speed and the fact that the pressing process is not a normal pressing process, although it is pressed, it may lead to quality defects. It is necessary to mark the suspicious quality section of the billet under the pressing of the billet head, so as to facilitate the later billet separation process for high-end customers.

[0079] like Figure 4The figure shows the trend of casting speed during the initial casting process of this casting machine. The normal production casting speed is controlled at 0.8 m / min. Through process tests, it was found that when the casting speed is below 0.7 m / min, even if the pressing process is used, the quality of the cast billet is still different from that of the normal casting speed process. Therefore, the cast billet produced by the casting speed below 0.7 m / min is regarded as the low casting speed casting billet range for the initial casting.

[0080] pass Figure 4 The casting speed tracking record shows that the duration of casting speeds less than 0.7 m / min is 6 minutes, and the duration tracked by the program is 4.1 m. That is, the low casting speed casting range is 4.1 m, which is longer than the 2.0 m range of the process without pressing. It can be seen that the casting of the billet after 2 m is pressed. However, the quality of the billet in the first 4.1 - 2.0 = 2.1 m of the pressed area is different from the quality of the billet in the normal casting speed process. It can be separated into different billets, or it can be removed or downgraded for use.

[0081] Figure 5 This is a summary and demonstration of the method for controlling the non-pressurization length of the billet head provided by the present invention through Example 1, and a visual comparison is made between the calibrated non-pressurization interval, the process non-pressurization interval, and the low-speed casting interval at the start of casting. The calibrated non-pressurization interval is set to 1.5m, and the process non-pressurization interval is set to 2.0m. The process non-pressurization interval must be larger than the calibrated non-pressurization interval to ensure that there is time for calibration. By setting the single-roller heavy pressing process at the end of low solidification, immediate pressing is achieved after the pressing conditions are met, and the non-pressurization interval of the billet head can be within 2.5m. In this example, the low-speed casting interval at the start of casting, tracked according to the process of increasing the casting speed at the start of casting, is 4.1m, which is larger than the process non-pressurization interval. However, this method can achieve precise positioning of the defective area (see Example 1). Figure 5 (See Example 1 in the text); Of course, the ideal situation is to optimize the initial casting process by appropriately increasing the casting speed, so that the low casting speed range for the initial casting is less than or equal to the non-pressing range, thus ensuring that the quality of all pressed-down castings is qualified (see Example 1 in the text). Figure 5 (The ideal situation).

[0082] It should be noted that this embodiment is merely a detailed description of the method for controlling the non-reduced length of the billet head and the method for reducing the length of the continuously cast billet provided by the present invention in practical applications, and does not limit the technical solution provided by the present invention.

[0083] As can be seen from the above specific embodiments, the method for controlling the non-pressurization length of the billet head and the pressing method for continuous casting billets provided by the present invention, by setting a calibration non-pressurization interval and a process non-pressurization interval at the billet head of the continuous casting billet, and ensuring that the length of the process non-pressurization interval is greater than the length of the calibration non-pressurization interval, then, during the billet drawing process, along the billet drawing direction, when the rear end of the calibration non-pressurization interval sequentially reaches the position of the straightening machine in the pressing section, the straightening machines at the corresponding positions are gradually calibrated. Then, when the rear end of the process non-pressurization interval passes the gradually calibrated straightening machines, the gradually calibrated straightening machines at the corresponding positions are pressed down, thereby controlling the non-pressurization length of the billet head. Located within the non-pressurization range of the process, this allows for the gradual calibration of the straightening machine and the immediate pressing of the billet head. Compared to the existing technology where all straightening machines are calibrated simultaneously and then rectified before pressing, this method controls the non-pressurization range of the billet head within the set process non-pressurization range, minimizing the non-pressurization range during the initial casting process and reducing the cost of scrap billets being recycled. Furthermore, the gradual calibration method ensures that even if a straightening machine fails to calibrate (marked as calibration failure), subsequent straightening machines can continue to be calibrated. During the subsequent pressing process, as long as the straightening machine that failed to calibrate is not used, no action is needed, thus minimizing the impact of calibration failure on pressing.

[0084] The method for controlling the non-reduction length of the billet head and the method for reducing the continuous casting billet according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the method for controlling the non-reduction length of the billet head and the method for reducing the continuous casting billet according to the present invention without departing from the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A method for controlling the length of the billet head that is not pressed down, characterized in that, Includes the following steps: A calibration non-reduction zone and a process non-reduction zone are set at the billet head of the continuously cast billet; wherein, the length of the process non-reduction zone is greater than the length of the calibration non-reduction zone; During the drawing process, along the drawing direction, when the rear end of the calibrated non-pressing section reaches the position of the straightening machine in the pressing section in sequence, the straightening machines at the corresponding positions are gradually calibrated in sequence; When the rear end of the non-pressurized section of the process passes the gradually calibrated tension leveler, the tension leveler at the corresponding position performs pressing down to control the non-pressurized length of the billet to be within the non-pressurized section of the process.

2. The method for controlling the non-pressed length of the billet head according to claim 1, characterized in that, The method further includes: In the billet head region where the drawing speed is lower than normal, a low solidification end reduction process is added to the preset two-stage reduction process table so that when the rear end of the non-reduction section passes the first tension leveler of the reduction section, the low solidification end reduction process causes the first tension leveler of the gradual calibration to perform reduction; wherein, the length of the low solidification end is less than the preset process solidification end in the two-stage reduction process table.

3. The method for controlling the non-pressed length of the billet head according to claim 2, characterized in that, In the process of adding a low solidification end reduction process to the preset two-stage reduction process table, The pressing process for the low solidification end is set to a single-roller pressing process.

4. The method for controlling the non-pressed length of the billet head according to claim 1, characterized in that, The method further includes: The length of the cast billet produced during the low casting speed period during the initial casting process is recorded as the questionable length, and the cast billet with the questionable length is marked as a quality questionable cast billet; wherein, the casting speed of the cast billet during the low casting speed period is less than the preset critical casting speed; the critical casting speed is less than the normal casting speed.

5. The method for controlling the non-pressed length of the billet head according to claim 4, characterized in that, exist During the process of tracking and recording the length of the cast billet generated during the low casting speed period in the initial casting process, the following formula is used to calculate the length of the cast billet generated during the low casting speed period: L t =V·Δt L=L pre +L t ; Among them, L t V is the length of the billet within the cycle; V is the casting speed within the cycle; Δt is the cycle time; L is the length of the billet produced during the cumulative low casting speed period; L pre The length of the billet produced during the low casting speed period before the current moment.

6. The method for controlling the non-pressed length of the billet head according to claim 4, characterized in that, The method further includes: The length of the billet with questionable quality is reduced by the length of the billet within the non-pressurization range of the process, and the billet is then classified as a quality-downgraded billet.

7. The method for controlling the non-pressed length of the billet head according to claim 1, characterized in that, The calibration non-pressurization range is set according to actual process requirements.

8. The method for controlling the non-pressed length of the billet head according to claim 1, characterized in that, The non-pressurization range of the process is set according to actual process requirements.

9. The method for controlling the non-pressed length of the billet head according to claim 1, characterized in that, The length of the calibration non-pressurization interval is 1.5m; the length of the process non-pressurization interval is 2.0m.

10. A method for reducing a continuously cast billet, characterized in that, During the continuous casting billet reduction process, the non-reduction length of the billet head is controlled by the method described in any one of claims 1-9.

Images