Method for controlling a slab heavy press-down sector

Abstract

The application provides a slab heavy pressing fan-shaped section control method, and belongs to the technical field of continuous casting, and comprises the following steps: in the process of slab heavy pressing, the first oil cylinder control force of the fan-shaped section is calculated according to the calculation principle that the output pressure of the single roller in the fan-shaped section just overcomes the outward bulging force of the cast blank in the static pressure area of the single roller; the second oil cylinder control force of the fan-shaped section is calculated according to the calculation principle that the output pressure of the fan-shaped section just overcomes the outward bulging force of the cast blank in the static pressure area of the fan-shaped section; the first oil cylinder control force and the second oil cylinder control force are respectively taken as the maximum control pressure and the minimum control pressure of the oil cylinder in the fan-shaped section; and the process control pressure of each oil cylinder in the fan-shaped section is set between the minimum control pressure and the maximum control pressure. The application can solve the problems that the existing technology is tracked and controlled according to the displacement mode, and the execution process of heavy pressing is prone to slab drawing accidents and reduces the service life of the equipment.

Description

Technical Field

[0001] This invention relates to the field of continuous casting technology, and more specifically, to a method for controlling the sector section of a slab under heavy pressure. Background Technology

[0002] During solidification, continuously cast slabs are prone to internal quality defects such as center segregation, porosity, and center shrinkage cavities, leading to substandard core quality in later rolled products. This is especially true for thick and extra-thick plates, where core defects are difficult to completely heal during rolling, resulting in failure to pass ultrasonic testing. Reducing the slab weight can compensate for the liquid volume shrinkage during solidification, effectively mitigating core segregation, porosity, and shrinkage cavities. Therefore, it is widely used in slab continuous casting. Furthermore, practical experience shows that heavy reduction can increase the core density of thick slabs, allowing for lower rolling ratios while still meeting testing requirements. Research indicates that by increasing the core density of thick plates through heavy reduction, the rolling ratio can be reduced from over 3.0 to below 2.0, significantly increasing the thickness of the rolled product. Conversely, this allows for thinning of the continuously cast slab, improving production efficiency and reducing production costs.

[0003] When using light reduction technology for slabs, thickness tracking and roll gap control are generally employed to ensure the accuracy of roll gap control. After reduction, the roll gap is adjusted in real-time based on the slab thickness tracking results, and displacement control is used. In practice, even with thickness tracking, there is a certain interval between data acquisition and distribution from the secondary model, resulting in a lag in the actual process. The thickness tracking cannot perfectly match the actual thickness, but due to the small reduction amount, it generally does not affect stable production. However, under heavy reduction, the tracking thickness differs significantly from the actual thickness due to the larger reduction amount. During the reduction process, the subsequent roll gap movement inevitably leads to excessive pressure on the non-drive rolls, causing a sharp increase in drawing resistance. Simultaneously, it inevitably results in insufficient pressure or even suspension of the drive rolls, leading to a sudden decrease in drawing force and potentially causing slab stagnation. Furthermore, excessive pressure on both the non-drive and drive rolls increases the stress on the rolls, reducing the service life of the rolls in the roll gap and increasing production costs.

[0004] As mentioned above, if the sector segment control method is based on displacement tracking control during the heavy pressure process of billet casting, the execution process under heavy pressure is prone to billet pulling accidents and reduced equipment service life.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide a control method for the sector segment under heavy pressure on a slab, so as to solve the problem that in the prior art, the sector segment control method is based on displacement tracking control during the heavy pressure process of the slab casting, which is prone to billet pulling accidents and reduced equipment service life.

[0007] This invention provides a method for controlling the sector segment under heavy pressure on a slab, comprising the following steps:

[0008] During the process of slab under heavy pressure, the first hydraulic cylinder control force of the sector segment is calculated by using the single-roller pressure calculation method, based on the principle that the output pressure of the single roller in the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure region of the single roller; and the second hydraulic cylinder control force of the sector segment is calculated by using the sector segment pressure calculation method, based on the principle that the output pressure of the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure region of the sector segment.

[0009] The control force of the first hydraulic cylinder and the control force of the second hydraulic cylinder are respectively taken as the maximum control pressure and the minimum control pressure of the hydraulic cylinder in the sector segment;

[0010] The process control pressure of each cylinder in the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy pressure of the slab.

[0011] Furthermore, a preferred embodiment is that the single-roller pressure calculation method includes:

[0012] The output pressure of the single roller within the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, so as to obtain the output pressure of the single roller.

[0013] The output pressure of the single roller is evenly distributed to the oil cylinders on both sides of the single roller to obtain the first oil cylinder control force of the sector segment.

[0014] Furthermore, a preferred embodiment is to make the output pressure of the single roller within the sector segment equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, in order to obtain the output pressure of the single roller, including:

[0015] The area where the contact points between the front and rear rollers adjacent to the single roller and the casting billet are located is taken as the static pressure area of ​​the single roller.

[0016] Based on the length and width of the static pressure region of the single roller, and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure region of the single roller under the action of the internal static pressure is obtained; wherein, the width of the static pressure region of the single roller is the width of the billet minus the thickness of the billet shell on both sides of the billet.

[0017] The output pressure of the single roller within the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, so as to obtain the output pressure of the single roller.

[0018] Furthermore, a preferred embodiment is that the method for calculating the pressure of the sector segment includes:

[0019] The output pressure of the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, so as to obtain the output pressure of the sector segment.

[0020] The output pressure of the sector segment is evenly distributed to each cylinder within the sector segment to obtain the second cylinder control force of the sector segment.

[0021] Furthermore, a preferred approach is to make the output pressure of the sector segment equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, in order to obtain the output pressure of the sector segment, including:

[0022] The area between the last pair of rollers of the previous sector segment adjacent to the sector segment and the first pair of rollers of the next sector segment adjacent to the sector segment is defined as the static pressure area of ​​the sector segment.

[0023] Based on the length and width of the static pressure region of the sector segment, and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure region of the sector segment under the action of the internal static pressure is obtained; wherein, the width of the static pressure region of the sector segment is the width of the billet minus the thickness of the billet shell on both sides of the billet.

[0024] The output pressure of the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, so as to obtain the output pressure of the sector segment.

[0025] Furthermore, a preferred approach is to set the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure during the control of the sector segment under heavy slab pressure.

[0026] The process control pressure of each cylinder within the sector segment is set to the minimum control pressure.

[0027] Furthermore, a preferred approach is to set the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure during the control of the sector segment under heavy slab pressure.

[0028] The process control pressure of each cylinder within the sector segment is set to the maximum control pressure.

[0029] Furthermore, a preferred approach is to set the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure during the control of the sector segment under heavy slab pressure.

[0030] The process control pressure of the hydraulic cylinder for the transmission rollers within the sector segment is brought close to the maximum control pressure setting.

[0031] The process control pressure of the hydraulic cylinders of the non-drive rollers within the sector segment is brought close to the minimum control pressure setting.

[0032] Furthermore, a preferred approach is to set the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure during the control of the sector segment under heavy slab pressure.

[0033] Along the billet pulling direction, the process control pressure of the hydraulic cylinders of the rollers in the sector section is set in a gradually increasing manner.

[0034] Furthermore, a preferred approach is to set the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure during the control of the sector segment under heavy slab pressure.

[0035] The process control pressure of the hydraulic cylinder of the transmission roller in the sector segment is set close to the maximum control pressure, and the process control pressure of the hydraulic cylinder of the transmission roller in the sector segment is set in a gradually increasing manner along the billet pulling direction.

[0036] The process control pressure of the hydraulic cylinders of the non-drive rollers in the sector segment is set close to the minimum control pressure setting, and the process control pressure of the hydraulic cylinders of the non-drive rollers in the sector segment is set in a gradually increasing manner along the billet pulling direction.

[0037] As can be seen from the above technical solution, the control method for the sector section under heavy slab pressure provided by this invention, during the process of heavy slab pressure, calculates the maximum and minimum control pressures of the hydraulic cylinders within the sector section based on the principle that the output pressure of the single roller within the sector section exactly overcomes the outward bulging force of the cast billet located in the static pressure region of the single roller, and the output pressure of the sector section exactly overcomes the outward bulging force of the cast billet located in the static pressure region of the sector section. This is achieved through single roller pressure calculation methods and sector section pressure calculation methods, thus obtaining the safe pressure range of the sector section. This ensures that the process control pressure of each hydraulic cylinder within the sector section is set within the safe pressure range for controlling the sector section under heavy slab pressure. By controlling the sector section pressure according to the safe pressure range, seamless fit between the sector section and the cast billet thickness can be achieved after pressure, eliminating the potential for unstable production caused by overpressure of non-drive rollers and drive rollers. It also protects the sector section equipment and effectively solves the problems of easy billet pulling accidents and reduced equipment lifespan in existing technologies.

[0038] To achieve the foregoing and related objectives, and in accordance with one or more aspects of the invention, the features described in detail below are included. Certain exemplary aspects of the invention are illustrated in detail below with reference to the accompanying drawings. 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

[0039] 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.

[0040] Figure 1 A flowchart illustrating the control method for the sector segment under heavy pressure on a slab according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the single-roller arrangement in the lower section of the slab under heavy pressure according to Embodiment 1 of the present invention;

[0042] Figure 3 This is a schematic diagram of the static pressure region of the No. 3 single roller and the static pressure region of the sector segment according to Embodiment 1 of the present invention. Detailed Implementation

[0043] 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.

[0044] In view of the aforementioned prior art, the sector segment control method in the process of casting billet under heavy pressure is based on displacement tracking control. The execution process under heavy pressure is prone to billet pulling accidents and reduced equipment service life. This invention proposes a control method for the sector segment under heavy pressure on slabs.

[0045] This invention addresses the instability inherent in existing technologies that use thickness tracking and roll gap control to control the sector segment during slab heavy pressing. It proposes a pressure-based sector segment control method to prevent slab stagnation accidents caused by increased drawing resistance and reduced drawing force due to inadequate or untimely tracking after heavy pressing. The proposed method for controlling the sector segment under heavy slab pressure provides a pressure calculation method. Maintaining the roll gap in the sector segment, without considering shrinkage, completely offsets the bulging caused by static pressure. Based on this, a method for calculating the safe pressure of the sector segment is proposed, whereby the output pressure of the sector segment under safe pressure is equal to the force causing bulging in the slab within the sector segment's area. By controlling pressure according to the safe pressure, seamless contact between the sector segment and the slab thickness is achieved after pressing, eliminating the potential for unstable production caused by overpressure of non-drive and drive rolls, and also protecting the sector segment equipment.

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] To illustrate the control method for the sector segment under heavy pressure of the slab provided by this invention Figure 1 The flowchart of a method for controlling a sector segment under heavy pressure on a slab according to an embodiment of the present invention is shown; Figure 2 The single-roller arrangement of the slab under heavy pressure section according to Embodiment 1 of the present invention is shown; Figure 3 The static pressure region of the No. 3 single roller and the static pressure region of the sector segment are shown according to Embodiment 1 of the present invention.

[0048] like Figure 1 As shown, the method for controlling the sector segment under heavy pressure of a slab provided by the present invention mainly includes the following steps:

[0049] Step S1: During the process of slab under heavy pressure, the first hydraulic cylinder control force of the sector segment is calculated by using the single roller pressure calculation method, based on the principle that the output pressure of the single roller in the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure area of ​​the single roller; and the second hydraulic cylinder control force of the sector segment is calculated by using the sector segment pressure calculation method, based on the principle that the output pressure of the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure area of ​​the sector segment.

[0050] Specifically, during the slab under heavy pressure, the output pressure of the single roller within the sector segment and the output pressure of the sector segment itself must offset the bulging force of the cast slab caused by the static pressure in the areas where the single roller and sector segment are located. Based on this calculation principle, single roller pressure and sector segment pressure calculations are performed to obtain the maximum and minimum control pressures of each cylinder in the sector segment. The control pressures of each cylinder within the sector segment are then set accordingly. That is, taking a single roller within the sector segment as the calculation unit, the control force of one cylinder on that single roller is calculated as the first cylinder control force of the sector segment; taking the entire sector segment as the calculation unit, the control force of each cylinder in the sector segment is calculated as the second cylinder control force of the sector segment.

[0051] As a preferred embodiment of the present invention, the single-roller pressure calculation method includes:

[0052] The output pressure of the single roller within the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, so as to obtain the output pressure of the single roller.

[0053] The output pressure of the single roller is evenly distributed to the oil cylinders on both sides of the single roller to obtain the first oil cylinder control force of the sector segment.

[0054] Specifically, the billet located in the static pressure zone of the single roll will generate an outward bulging force under the action of internal static pressure. That is, the bulging force is equal to the static pressure. According to production data, those skilled in the art can calculate the static pressure of the billet located in the static pressure zone of the single roll, thereby obtaining the outward bulging force of the billet located in the static pressure zone of the single roll, so as to obtain the output pressure of the single roll. The single roll generally has a hydraulic cylinder on each side. Therefore, by distributing the output pressure of the single roll evenly to the hydraulic cylinders on both sides of the single roll, the control force of each hydraulic cylinder on the single roll can be obtained. The control force of the hydraulic cylinder is used as the first hydraulic cylinder control force of the sector segment where the single roll is located.

[0055] As a preferred embodiment of the present invention, the output pressure of the single roller within the sector segment is equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, in order to obtain the output pressure of the single roller, including:

[0056] The area where the contact points between the front and rear rollers adjacent to the single roller and the casting billet are located is taken as the static pressure area of ​​the single roller.

[0057] Based on the length and width of the static pressure zone of the single roll and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure zone of the single roll under the action of the internal static pressure is obtained; wherein, the width of the static pressure zone of the single roll is the width of the billet minus the thickness of the billet shell on both sides of the billet.

[0058] The output pressure of the single roller within the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, so as to obtain the output pressure of the single roller.

[0059] Specifically, the static pressure region of a single roll is defined as the area between the contact point between the preceding single roll and the billet and the contact point between the following single roll and the billet. When using the single roll pressure calculation method, the single roll is preferably located in the middle of the sector segment. The length and width of the static pressure region of the single roll, as well as the internal static pressure of the billet, are readily available production data. Based on this data, the internal static pressure of the billet located in the static pressure region of the single roll, i.e., the outward bulging force, can be calculated. This ensures that the output pressure of the single roll within the sector segment is equal to the outward bulging force of the billet located in the static pressure region of the single roll under the action of the internal static pressure. At this point, the single roll can overcome the outward bulging of the billet located in the static pressure region of the single roll, thus obtaining the output pressure of the single roll.

[0060] As a preferred embodiment of the present invention, the method for calculating the pressure of the sector segment includes:

[0061] The output pressure of the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, so as to obtain the output pressure of the sector segment.

[0062] The output pressure of the sector segment is evenly distributed to each cylinder within the sector segment to obtain the second cylinder control force of the sector segment.

[0063] Specifically, the billet located in the static pressure region of the sector segment will generate an outward bulging force under the action of internal static pressure. That is, the bulging force is equal to the static pressure. According to production data, those skilled in the art can calculate the static pressure of the billet located in the static pressure region of the sector segment, thereby obtaining the outward bulging force of the billet located in the static pressure region of the sector segment, so as to obtain the output pressure of the sector segment. The sector segment may include multiple hydraulic cylinders. Therefore, by evenly distributing the output pressure of the sector segment to each hydraulic cylinder in the sector segment, the control force of each hydraulic cylinder in the sector segment can be obtained. The control force of the hydraulic cylinder is used as the second hydraulic cylinder control force of the sector segment.

[0064] As a preferred embodiment of the present invention, the output pressure of the sector segment is equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, so as to obtain the output pressure of the sector segment, including:

[0065] The area between the last pair of rollers of the previous sector segment adjacent to the sector segment and the first pair of rollers of the next sector segment adjacent to the sector segment is defined as the static pressure area of ​​the sector segment.

[0066] Based on the length and width of the static pressure region of the sector segment, and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure region of the sector segment under the action of the internal static pressure is obtained; wherein, the width of the static pressure region of the sector segment is the width of the billet minus the thickness of the billet shell on both sides of the billet.

[0067] The output pressure of the sector segment is made equal to the outward bulging force of the billet under the action of internal static pressure in the static pressure region of the sector segment, so as to obtain the output pressure of the sector segment.

[0068] Specifically, the area between the last pair of rollers of the previous sector segment and the first pair of rollers of the next sector segment is defined as the static pressure region of the sector segment. When using the sector segment pressure calculation method, the length and width of the static pressure region of the sector segment, as well as the internal static pressure of the billet, are all available production data. Based on the above data, the internal static pressure of the billet located in the static pressure region of the sector segment, i.e., the outward bulging force, can be calculated. This ensures that the output pressure within the sector segment is equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of the internal static pressure. At this point, the sector segment can overcome the outward bulging of the billet located in the static pressure region of the sector segment, thus obtaining the output pressure of the sector segment.

[0069] Step S2: The control force of the first cylinder and the control force of the second cylinder are respectively taken as the maximum control pressure and minimum control pressure of the cylinders in the sector segment.

[0070] Specifically, the static pressure region where a single roller is located within a sector segment is used as the calculation unit to calculate the control pressure of a single cylinder of that single roller, which is then used as the maximum control pressure of the cylinders within the sector segment where that single roller is located. The static pressure region where the sector segment is located is used as the calculation unit to calculate the control pressure of each cylinder within that sector segment, which is then used as the maximum control pressure of the cylinders within that sector segment, thereby obtaining the safe pressure range during the sector segment control process.

[0071] Step S3: Set the process control pressure of each cylinder in the sector section between the minimum control pressure and the maximum control pressure to control the sector section under heavy pressure of the slab.

[0072] Specifically, the process control pressure of each cylinder within the sector segment is set between the minimum and maximum control pressure, i.e., within the safe pressure range, to control the sector segment under heavy slab pressure. By setting the process control pressure of each cylinder within the sector segment within the safe pressure range, seamless fit between the sector segment and the slab thickness can be achieved after pressing, eliminating the potential for unstable production caused by overpressure of non-drive rollers and drive rollers, while also protecting the sector segment equipment.

[0073] As a preferred embodiment of the present invention, the process control pressure of each cylinder within the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy slab pressure.

[0074] Set the process control pressure of each cylinder in the sector to the minimum control pressure.

[0075] Specifically, the process control pressure of each cylinder in the sector section is controlled according to the minimum control pressure, which can both eliminate the bulging of the billet and reduce the resistance of billet pulling.

[0076] As a preferred embodiment of the present invention, the process control pressure of each cylinder within the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy slab pressure.

[0077] Set the process control pressure of each cylinder in the sector section to the maximum control pressure.

[0078] Specifically, the process control pressure of each cylinder in the sector section is controlled according to the maximum control pressure, which can both eliminate the bulging of the billet and increase the pulling force.

[0079] As a preferred embodiment of the present invention, the process control pressure of each cylinder within the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy slab pressure.

[0080] The process control pressure of the hydraulic cylinder for the transmission rollers within the sector segment is brought close to the maximum control pressure setting.

[0081] The process control pressure of the hydraulic cylinders of the non-drive rollers in the sector section is brought close to the minimum control pressure setting.

[0082] Specifically, considering both the drawing resistance and the drawing force, the sector section with drive rollers can be controlled by a process pressure closer to the maximum control pressure, while the non-drive rollers can be controlled by a process pressure closer to the minimum control pressure.

[0083] As a preferred embodiment of the present invention, the process control pressure of each cylinder within the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy slab pressure.

[0084] Along the billet pulling direction, the process control pressure of the hydraulic cylinders of the rollers in the sector section is set in a gradually increasing manner.

[0085] Specifically, considering the creep characteristics and time-dependent nature of the bulge, the process pressure of the sector segment can be set differently from front to back, such as gradually increasing, but the process pressure needs to be controlled between the minimum control pressure and the maximum control pressure.

[0086] As a preferred embodiment of the present invention, the process control pressure of each cylinder within the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy slab pressure.

[0087] The process control pressure of the hydraulic cylinder of the transmission roller in the sector section is set close to the maximum control pressure setting, and the process control pressure of the hydraulic cylinder of the transmission roller in the sector section is set in a gradually increasing manner along the billet pulling direction.

[0088] The process control pressure of the hydraulic cylinders of the non-drive rollers in the sector section is set close to the minimum control pressure setting, and the process control pressure of the hydraulic cylinders of the non-drive rollers in the sector section is set in a gradually increasing manner along the billet pulling direction.

[0089] Specifically, the process pressure of the sector segment can also be set to take into account both the gradual increase and the driving rollers and non-driving rollers.

[0090] By calculating the output pressure of a single roller within the fan-shaped section to overcome the outward bulging force of the billet located in the static pressure zone of the single roller, and by calculating the output pressure of the fan-shaped section to overcome the outward bulging force of the billet located in the static pressure zone of the fan-shaped section, the maximum and minimum control pressures of the hydraulic cylinders within the fan-shaped section are obtained through single-roller pressure calculation methods and fan-shaped section pressure calculation methods, respectively. This yields the safe pressure range of the fan-shaped section, allowing the process control pressure of each hydraulic cylinder within the fan-shaped section to be set within this safe pressure range for controlling the fan-shaped section under slab heavy pressure. By controlling the fan-shaped section pressure according to the safe pressure range, seamless contact between the fan-shaped section and the billet thickness can be achieved after pressing, eliminating the potential for unstable production caused by overpressure of non-drive rollers and drive rollers. It also protects the fan-shaped section equipment, effectively solving the problems of billet pulling accidents and reduced equipment lifespan in existing technologies.

[0091] The present invention proposes a method for controlling the sector segment under heavy pressure on slabs, which provides a scheme for calculating the safe pressure of the sector segment. By determining the safe pressure range of the sector segment according to this scheme, and adopting a pressure control method, the occurrence of billet pulling accidents during the execution of the displacement control method based on thickness tracking under heavy pressure can be avoided.

[0092] This invention can also avoid the reduction in service life caused by the increase in the peak pressure of the fan-shaped roller, thereby achieving the effect of improving the service life of the equipment and reducing production costs.

[0093] To better illustrate the application of the control method for the sector segment under heavy pressure of the slab provided by the present invention, the following specific embodiments are provided:

[0094] Example 1

[0095] Taking a 300×1650mm thick plate casting machine in a steel plant as an example, under heavy pressure, the fan-shaped section is located in the horizontal section, such as... Figure 2 As shown, the heavy-pressure sector section has 5 pairs of independent rollers, each with a diameter of 420mm. Each roller has a hydraulic cylinder on its left and right sides, with two cylinders controlling the pressing action. Each cylinder has a diameter of 360mm. The distance between roller #1 and the last roller of the previous sector section is 470mm; the distance between rollers #1 to #5 is 470mm; and the distance between roller #5 and the first roller of the next sector section is 470mm. The height of the outer arc of the horizontal section billet from the liquid surface of the crystallizer is 14.16m, meaning the static pressure head is 14.16m.

[0096] 1. Single Roller Pressure Calculation Method

[0097] Each pair of single rollers must be able to overcome the outward bulging of the billet caused by the internal static pressure in its respective static pressure zone in order to ensure the shape of the billet; this is the core idea of ​​this invention. Specifically, as follows... Figure 3 As shown, the static pressure range of single roller #3 is the area formed between the contact point between single roller #2 and the billet and the contact point between single roller #4 and the billet. The length of this area is 470mm + 470mm = 0.94m. Under static pressure, the billet in this area will bulge outwards. The external force applied by single roller #3 must be able to counteract the resultant static pressure force inside the billet in this area. Based on this, Table 1 provides the detailed process and data for calculating the single roller pressure. Under a static pressure head of 14.16m, a uniformly distributed static pressure load of 1104480 N / m will exist inside the billet in this area. 2 The total pressure exerted on the billet in the designated area (width x length range) is 129.8T. The two cylinders of the #3 single roller must output a considerable external force to counteract this total pressure and prevent the billet from bulging. That is, each cylinder needs to output 129.8T / 2 = 64.9T, which, based on a cylinder diameter of 360mm, requires approximately 6.3MPa of cylinder pressure. Calculations show that, in the given embodiment, the pressure of the #3 single roller is 129.8T, and the cylinder pressure is 6.3MPa. Since the roller spacing of #1 to #5 single rollers is the same as that of #3, the single roller pressures of the other rollers are the same as those calculated for #3.

[0098] 2. Calculation method for pressure in sector segment

[0099] The fan-shaped segment must overcome the outward bulging caused by the internal static pressure of the billet in its area to ensure the billet's shape. For example... Figure 3As shown, the static pressure area of ​​the sector segment under this heavy pressure is the area formed by the last pair of rollers of the previous sector segment and the first pair of rollers of the next sector segment, specifically a length range of 470mm × 6 = 2.82m. The total pressure generated by the casting in this area is shown in Table 1, that is, the total pressure calculated for the sector segment is 389.3T. This sector segment has a total of 5 pairs of single rollers, each pair of single rollers has two hydraulic cylinders, for a total of 10 hydraulic cylinders. Therefore, each hydraulic cylinder needs to bear a force of 389.3T / 10 = 38.93T, which requires a hydraulic cylinder pressure of approximately 3.8MPa based on a cylinder diameter of 360mm.

[0100] project Single roller pressure calculation Sector pressure calculation <![CDATA[Liquid steel density (kg / m 3 )]]> 7800 7800 Acceleration due to gravity (N / kg) 10 10 Static pressure head (m) 14.16 14.16 <![CDATA[Static pressure (N / m 2 )]]> 1104480 1104480 Width range (m) 1.25 1.25 Length range (m) 0.94 2.82 Total pressure (T) 129.8 389.3

[0101] Table 1

[0102] Wherein: the width of the billet is 1650mm minus the thickness of the billet shell on both sides of the billet, which is 400mm, which is 1.65-0.4=1.25m.

[0103] The calculation results above show that the total pressure and cylinder pressure of each pair of single rollers obtained by the single roller pressure calculation method are greater than those obtained by the sector segment pressure calculation method. This is because the single roller pressure and sector segment pressure calculations cover many areas repeatedly. Obviously, the cylinder pressure value cannot be less than the cylinder pressure obtained by the sector segment pressure calculation method. The cylinder pressure obtained by the sector segment pressure calculation method is taken as the minimum control pressure, which is 3.8 MPa in this embodiment; the cylinder pressure obtained by the single roller pressure calculation method is taken as the maximum control pressure, which is 6.3 MPa in this embodiment.

[0104] Based on the above calculation results of maximum and minimum control pressures, the method for determining the process control pressure of the hydraulic cylinder within the sector segment is as follows:

[0105] 1. The value of the hydraulic cylinder process control pressure cannot be less than the hydraulic cylinder pressure obtained by the sector segment pressure calculation method, i.e., minimum control pressure control. Specifically, in Example 1, this means that the pressure of each hydraulic cylinder on the sector segment is not less than the minimum control pressure of 3.8 MPa, and the sector segment pressure control can be performed according to the minimum control pressure.

[0106] 2. The hydraulic cylinder process control pressure can also be controlled according to the maximum control pressure. Specifically, in Example 1, the maximum control pressure is 6.3 MPa. Obviously, this method is too conservative and may lead to thinning of the cast billet.

[0107] 3. Since the bulging deformation has a creep effect and is a gradual process, there is a tendency for the bulging to gradually increase within a sector segment. Accordingly, the hydraulic cylinder pressure of each roller within the sector segment can be gradually increased. Specifically, in Example 1, the hydraulic cylinder pressures of rollers 1 to 5 in the sector segment under heavy pressure can be set to 3.8MPa, 4.0MPa, 4.2MPa, 4.4MPa, and 4.6MPa respectively, while ensuring that the hydraulic cylinder pressure is between the minimum control pressure and the maximum control pressure.

[0108] 4. Considering that the drive rollers require greater pressure to output a larger drawing force and thus ensure smooth production, the drive rollers can be controlled with the maximum control pressure, while the non-drive rollers can be controlled with the minimum control pressure. Specifically, in this embodiment, rollers #1 and #3 are driven, while rollers #2, #4, and #5 are not. Rollers #1 and #3 can be controlled with the maximum control pressure of 6.3 MPa, balancing bulging and maximum drawing force output; rollers #2, #4, and #5 can be controlled with the minimum control pressure of 3.8 MPa, balancing bulging and minimum drawing resistance.

[0109] Although the method provided in this embodiment of the invention is described in the context of a heavy-pressure section where each pair of rollers in a sector has a hydraulic cylinder, the method is also applicable to all types of sector sections. For example, some traditional sector sections do not have a pair of hydraulic cylinders on all rollers; instead, only four clamping hydraulic cylinders are located at the front and rear of the sector section frame, and a pair of hydraulic cylinders are arranged on a pair of drawing rollers in the middle area of ​​the sector section, for a total of six hydraulic cylinders. The pressure of the hydraulic cylinders on the drawing rollers is calculated according to the single-roller pressure method in this invention, and the pressure of the remaining four clamping hydraulic cylinders is the total pressure of the sector section minus the pressure on the drawing rollers before distribution. The specific distribution method is the same as the distribution method in the above embodiment of the invention.

[0110] As can be seen from the above specific embodiments, the control method for the sector section under heavy slab pressure provided by the present invention, through the calculation principle that the output pressure of the single roller in the sector section exactly overcomes the outward bulging force of the billet located in the static pressure area of ​​the single roller, and the output pressure of the sector section exactly overcomes the outward bulging force of the billet located in the static pressure area of ​​the sector section, respectively, obtains the maximum control pressure and minimum control pressure of the hydraulic cylinder in the sector section through the single roller pressure calculation method and the sector section pressure calculation method, that is, obtains the safe pressure range of the sector section, so that the process control pressure of each hydraulic cylinder in the sector section is set within the safe pressure range of the sector section, thereby controlling the sector section under heavy slab pressure. By controlling the sector section pressure according to the safe pressure range, seamless fit between the sector section and the billet thickness can be achieved after pressing, eliminating the stable production hazards caused by overpressure of non-drive rollers and drive rollers, and also protecting the sector section equipment, effectively solving the problems of easy billet pulling accidents and reduced equipment service life in the prior art.

[0111] The method for controlling the sector segment under heavy slab pressure according to the present invention has 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 sector segment under heavy slab pressure according to the present invention without departing from the scope of the 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 sector segment under heavy pressure on a slab, characterized in that, Includes the following steps: During the process of slab pressure, the first hydraulic cylinder control force of the sector segment is calculated using a single-roller pressure calculation method, based on the principle that the output pressure of the single roller within the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure region of the single roller. The second hydraulic cylinder control force of the sector segment is calculated using a sector segment pressure calculation method, based on the principle that the output pressure of the sector segment exactly overcomes the outward bulging force of the slab located in the static pressure region of the sector segment. The single-roller pressure calculation method includes: The area where the contact points between the front and rear rollers adjacent to the single roller and the casting billet are located is taken as the static pressure area of ​​the single roller. Based on the length and width of the static pressure region of the single roller, and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure region of the single roller under the action of the internal static pressure is obtained; wherein, the width of the static pressure region of the single roller is the width of the billet minus the thickness of the billet shell on both sides of the billet. The output pressure of the single roller within the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the single roller under the action of internal static pressure, so as to obtain the output pressure of the single roller. The output pressure of the single roller is evenly distributed to the oil cylinders on both sides of the single roller to obtain the first oil cylinder control force of the sector segment; The method for calculating the pressure of the sector segment includes: The area between the last pair of rollers of the previous sector segment adjacent to the sector segment and the first pair of rollers of the next sector segment adjacent to the sector segment is defined as the static pressure area of ​​the sector segment. Based on the length and width of the static pressure region of the sector segment, and the pre-obtained internal static pressure of the billet, the outward bulging force of the billet located in the static pressure region of the sector segment under the action of the internal static pressure is obtained; wherein, the width of the static pressure region of the sector segment is the width of the billet minus the thickness of the billet shell on both sides of the billet. The output pressure of the sector segment is made equal to the outward bulging force of the billet located in the static pressure region of the sector segment under the action of internal static pressure, so as to obtain the output pressure of the sector segment. The output pressure of the sector segment is evenly distributed to each cylinder within the sector segment to obtain the second cylinder control force of the sector segment; The control force of the first hydraulic cylinder and the control force of the second hydraulic cylinder are respectively taken as the maximum control pressure and the minimum control pressure of the hydraulic cylinder in the sector segment; The process control pressure of each cylinder in the sector segment is set between the minimum control pressure and the maximum control pressure to control the sector segment under heavy pressure of the slab.

2. The method for controlling the sector-shaped section under heavy pressure on a slab according to claim 1, characterized in that, In the process of controlling the sector segment under heavy slab pressure by setting the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure, The process control pressure of each cylinder within the sector segment is set to the minimum control pressure.

3. The method for controlling the sector-shaped section under heavy pressure on a slab according to claim 1, characterized in that, In the process of controlling the sector segment under heavy slab pressure by setting the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure, The process control pressure of each cylinder within the sector segment is set to the maximum control pressure.

4. The method for controlling the sector-shaped section under heavy pressure on a slab according to claim 1, characterized in that, In the process of controlling the sector segment under heavy slab pressure by setting the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure, The process control pressure of the hydraulic cylinder for the transmission rollers within the sector segment is brought close to the maximum control pressure setting. The process control pressure of the hydraulic cylinders of the non-drive rollers in the sector section is brought close to the minimum control pressure setting.

5. The method for controlling the sector-shaped section under heavy pressure on a slab according to claim 1, characterized in that, In the process of controlling the sector segment under heavy slab pressure by setting the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure, Along the billet pulling direction, the process control pressure of the hydraulic cylinders of the rollers in the sector section is set in a gradually increasing manner.

6. The method for controlling the sector-shaped section under heavy pressure on a slab according to claim 1, characterized in that, In the process of controlling the sector segment under heavy slab pressure by setting the process control pressure of each cylinder within the sector segment between the minimum control pressure and the maximum control pressure, The process control pressure of the hydraulic cylinder of the transmission roller in the sector segment is set close to the maximum control pressure, and the process control pressure of the hydraulic cylinder of the transmission roller in the sector segment is set in a gradually increasing manner along the billet pulling direction. The process control pressure of the hydraulic cylinders of the non-drive rollers in the sector segment is set close to the minimum control pressure setting, and the process control pressure of the hydraulic cylinders of the non-drive rollers in the sector segment is set in a gradually increasing manner along the billet pulling direction.

Images