Large-scale pressing device and method for sector-shaped sections of slab

Abstract

This invention provides a device and method for large-scale pressing of a sector segment of a slab, comprising: a pressing roller and a pressing control device; the pressing roller includes at least two pairs of drive rollers and a pair of free rollers disposed between adjacent drive rollers; each pair of drive rollers includes an upper drive roller and a lower drive roller, and each pair of free rollers includes an upper free roller and a lower free roller; each pair of drive rollers is connected to a transmission device, which drives the upper and lower drive rollers to rotate; the pressing control device includes a first pressing cylinder disposed on the upper drive roller and a second pressing cylinder disposed on the upper free roller. This invention can solve the problems of high precision requirements for pressing position, high load-bearing requirements for the frame of the sector segment, and the tendency for bulging in current large-scale pressing techniques for sector segments of slabs.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and more specifically, to a device and method for large-scale pressing of a slab into a sector. Background Technology

[0002] To improve the central porosity of slabs and produce thicker plates using a smaller compression ratio, both domestic and international manufacturers have adopted a method of applying large reductions to the slab during continuous casting. Implementing this technology involves working on the existing slab sector segment. One approach is to increase the rigidity of the sector segment itself and the clamping capacity, using the entire sector segment to apply the large reduction. The structure of the sector segment using this method is not fundamentally different from that of a conventional slab sector segment. Another approach is to apply the reduction using a pair of rollers within the sector segment. This method uses rollers with a large diameter to prevent roller deformation.

[0003] Currently, there are many problems and shortcomings when implementing large-scale compression on these types of sector segments:

[0004] 1) Due to the large amount of compression, generally 10-15mm, the frame of the sector section is subjected to a large force, reaching thousands of tons. Conventional structures cannot guarantee the accuracy of the frame, and permanent deformation will occur after a period of use.

[0005] 2) When using one pair of rollers to press down, the pressing position needs to be very accurate, but the solidification endpoint of the sector segment often varies greatly. This method often presses down when the billet is almost completely solidified, so the pressing force is very large. To avoid deformation, the roller diameter is generally selected to be around 700 mm.

[0006] 3) Due to the large roller diameter and the large gap between the front and rear rollers, bulging is likely to occur when the pulling speed is high, leading to cracks. Therefore, this solution is not very applicable.

[0007] In summary, the use of existing technologies has problems such as high requirements for the precision of the pressing position, high requirements for the frame bearing capacity of the sector segment, and the tendency for bulging. Summary of the Invention

[0008] In view of the above problems, the purpose of this invention is to provide a device and method for large-scale pressing of slab sector segments, so as to solve the problems of high precision requirements for pressing position, high requirements for the frame bearing capacity of sector segments, and easy occurrence of bulging phenomenon in the current large-scale pressing technology of slab sector segments.

[0009] This invention provides a large pressing device for a sector segment of a slab, comprising: pressing rollers and pressing control device; wherein, the pressing rollers include at least two pairs of drive rollers and a pair of free rollers disposed between adjacent drive rollers; each pair of drive rollers includes an upper drive roller and a lower drive roller, and each pair of free rollers includes an upper free roller and a lower free roller; each pair of drive rollers is connected to a transmission device, which drives the upper drive roller and the lower drive roller to rotate; the pressing control device includes a first pressing cylinder disposed on the upper drive roller and a second pressing cylinder disposed on the upper free roller.

[0010] Furthermore, in a preferred embodiment, the pressing roller comprises three pairs of drive rollers and two pairs of free rollers.

[0011] Furthermore, a preferred embodiment is that the diameter of the drive roller is 400-450 mm; and / or the diameter of the free roller is 400-450 mm.

[0012] Furthermore, a preferred embodiment is that the pressure values ​​of both the drive roller and the free roller are 200 to 300 tons.

[0013] Furthermore, a preferred embodiment is that the first pressing cylinder is disposed at both ends of each pair of drive rollers; and / or, the second pressing cylinder is disposed at both ends of each pair of free rollers.

[0014] Furthermore, a preferred embodiment is that a first displacement sensor is provided in the first pressing cylinder; the upper drive roller presses down the fan-shaped segment of the billet using the displacement value obtained by the first displacement sensor; and / or, a second displacement sensor is provided in the second pressing cylinder; the upper free roller presses down the fan-shaped segment of the billet using the displacement value obtained by the second displacement sensor.

[0015] Furthermore, a preferred embodiment is that a first pressure sensor is provided in the first pressing cylinder; the upper drive roller presses down the sector segment of the billet using the pressure value obtained by the first pressure sensor; and / or, a second pressure sensor is provided in the second pressing cylinder; the upper free roller presses down the sector segment of the billet using the pressure value obtained by the second pressure sensor.

[0016] Furthermore, a preferred embodiment is that the distance between adjacent drive rollers and free rollers is 430–480 mm.

[0017] This invention provides a method for large-scale reduction of a sector segment of a slab, which utilizes the large-scale reduction device for the sector segment of a slab as described above to perform large-scale reduction of the sector segment, including the following steps:

[0018] Based on the solid fraction of the billet in the range of 0.3 to 0.8, the billet pulling resistance experienced by the large-reduction device of the sector section of the billet under large reduction is determined;

[0019] The initial value of the transmission device is determined based on the billet pulling resistance to complete the large reduction of the sector segment of the slab. When the large reduction rollers for the sector segment of the slab are any pair of drive rollers, the transmission device connected to the remaining drive rollers provides pressure for the billet pulling resistance. The free rollers that do not perform large reduction use hot billet pressing to reduce the slab. When the large reduction rollers for the sector segment of the slab are free rollers, the transmission device connected to the drive rollers provides pressure for the billet pulling resistance.

[0020] Furthermore, in a preferred embodiment, the formula for calculating the billet pulling resistance experienced by the large-reduction device of the slab sector during large reduction is: F=2σδ(2Rh-h 2 ) / R;

[0021] Where σ is the average deformation resistance, δ is the thickness of the billet, R is the radius of the pressing roll, h is half of the pressing amount, and F is the billet pulling resistance generated by the pressing of the pressing roll.

[0022] As can be seen from the above technical solution, the slab sector large pressing device and method provided by the present invention, by setting at least two pairs of driving rollers and free rollers set between adjacent driving rollers in the sector sector, and by setting each pair of pressing rollers with a separate pressing cylinder, allows each pair of pressing rollers to perform pressing independently. Since multiple pairs of pressing rollers work together, the roller diameter of the individual pressing roller can be reduced, and the roller distance between adjacent pressing rollers is small, effectively avoiding the occurrence of bulging. Pressing can be carried out within the solid fraction range. Since the slab is not fully solidified, the required pressing force is small, reducing the rigidity requirement of the sector sector frame. Unlike conventional sector sectors with only one pair of driving rollers, since the billet pulling resistance is large during large pressing, the present invention uses at least two pairs of driving rollers. When pressing, only one pair of pressing rollers is used for pressing. According to the change of solid fraction at the center of the slab, when using driving rollers or free rollers to perform single-roll pressing, the other driving rollers provide corresponding pressure to provide a sufficiently large driving force, effectively avoiding the occurrence of billet stagnation.

[0023] 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

[0024] 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. In the drawings:

[0025] Figure 1This is a schematic diagram of the large pressing device for the sector section of a slab according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the drive roller according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the connection between the pressing roller and the transmission device according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic flowchart of a method for large-scale reduction of a slab sector according to an embodiment of the present invention.

[0029] In the attached drawings, 1-drive roller, 11-upper drive roller, 12-lower drive roller, 2-free roller, 21-upper free roller, 22-lower free roller, 3-transmission device, 41-first pressing cylinder, 42-second pressing cylinder.

[0030] In the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0031] 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.

[0032] In response to the aforementioned problems with the current large-scale pressing technology for slab sector segments, such as high precision requirements for pressing position, high requirements for the frame bearing capacity of sector segments, and the tendency to bulge, a device and method for large-scale pressing of slab sector segments is proposed.

[0033] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] To illustrate the slab sector large-segment pressing device and method provided by the present invention Figure 1 The structure of a large pressing device for the sector section of a slab according to an embodiment of the present invention is shown; Figure 2 The structure of the drive roller according to an embodiment of the present invention is shown; Figure 3 The structure of the pressure roller connected to the transmission device according to an embodiment of the present invention is shown. Figure 4 The flowchart of a method for large-scale reduction of a slab sector according to an embodiment of the present invention is shown.

[0035] like Figures 1 to 4As shown in the figure, the large pressing device for the sector segment of the slab provided by the present invention includes: pressing rollers and pressing control device; wherein, the pressing rollers include at least two pairs of drive rollers 1 and a pair of free rollers 2 disposed between adjacent drive rollers 1; each pair of drive rollers 1 includes an upper drive roller 11 and a lower drive roller 12, and each pair of free rollers 2 includes an upper free roller 21 and a lower free roller 22; each pair of drive rollers 1 is connected to a transmission device 3, which drives the upper drive roller 11 and the lower drive roller 12 to rotate; the pressing control device includes a first pressing cylinder 41 disposed on the upper drive roller 11 and a second pressing cylinder 42 disposed on the upper free roller 21.

[0036] By setting at least two pairs of drive rollers 1 and free rollers 2 between adjacent drive rollers 1 in the fan-shaped section, and by setting each pair of pressing rollers 1 with a separate pressing cylinder, each pair of pressing rollers can be pressed independently. Since multiple pairs of pressing rollers work together, the roller diameter of the individual pressing roller can be reduced, and the roller distance between adjacent pressing rollers is small, effectively avoiding the occurrence of bulging. Pressing can be carried out within the range of solid fraction. Since the billet is not fully solidified, the required pressing force is small, reducing the rigidity requirement of the fan-shaped section frame. Unlike conventional fan-shaped sections with only one pair of drive rollers, since the billet pulling resistance is large during large pressing, this invention uses at least two pairs of drive rollers 1. When pressing, only one pair of pressing rollers is used for pressing. According to the change of solid fraction at the center of the billet, when using drive roller 1 or free roller 2 to carry out single-roll pressing, the other drive rollers 1 provide corresponding pressure to provide a sufficiently large driving force, effectively avoiding the occurrence of billet stagnation.

[0037] In a preferred embodiment of the present invention, the pressing rollers include three pairs of drive rollers 1 and two pairs of free rollers 2. Alternatively, using five pairs of pressing rollers, with three pairs of drive rollers 1 and two pairs of free rollers 2, achieves the best combination effect while also optimizing the space occupied.

[0038] As a preferred embodiment of the present invention, the diameter of the drive roller 1 is 400-450 mm; and / or, the diameter of the free roller 2 is 400-450 mm. The diameters of the drive roller 1 and the free roller 2 are smaller than the diameters of the multiple drive rollers used in the prior art. Smaller roller diameters are beneficial for reducing the roller spacing between adjacent rollers and avoiding bulging.

[0039] The pressure values ​​of both drive roller 1 and free roller 2 are 200-300 tons. The pressure values ​​are lower than those using a pair of drive rollers to avoid damage to the frame of the sector section.

[0040] In a preferred embodiment of the present invention, a first pressing cylinder 41 is disposed at both ends of each pair of drive rollers 1; and / or, a second pressing cylinder 42 is disposed at both ends of each pair of free rollers 2. This allows both ends of the pressing rollers to press down simultaneously, resulting in a better pressing effect. Each pair of pressing rollers can be controlled to perform individual pressing.

[0041] In a preferred embodiment of the present invention, a first displacement sensor is provided in the first pressing cylinder 41; the upper drive roller 11 presses down the sector segment of the billet based on the displacement value obtained by the first displacement sensor; and / or, a second displacement sensor is provided in the second pressing cylinder 42; the upper free roller 21 presses down the sector segment of the billet based on the displacement value obtained by the second displacement sensor. The pressing displacement value of the pressing roller can be transmitted by the sensor, and then the pressing operation of the pressing roller is controlled according to the pressing displacement value.

[0042] In a preferred embodiment of the present invention, a first pressure sensor is provided in the first pressing cylinder 41; the upper drive roller 11 presses down the sector segment of the billet based on the pressure value obtained by the first pressure sensor; and / or, a second pressure sensor is provided in the second pressing cylinder 42; the upper free roller 21 presses down the sector segment of the billet based on the pressure value obtained by the second pressure sensor. The pressing process of the pressing roller can also be controlled by setting the pressure value. Pressure sensors and displacement sensors can be simultaneously installed in the pressing cylinders to achieve a dual control mode of pressure and displacement.

[0043] In a preferred embodiment of the present invention, the distance between adjacent drive rollers 1 and free rollers 2 is 430–480 mm. A smaller distance effectively prevents bulging from occurring.

[0044] This invention provides a method for large-scale reduction of a sector segment of a slab, which utilizes the large-scale reduction device for the sector segment of a slab as described above to perform large-scale reduction of the sector segment, including the following steps:

[0045] S1. Based on the solid fraction of the billet in the range of 0.3 to 0.8, determine the billet pulling resistance experienced by the large-reduction device of the sector section of the slab under large reduction.

[0046] S2. Determine the initial value of the transmission device based on the billet pulling resistance to complete the large reduction of the sector segment of the slab; wherein, when the large reduction rollers for the sector segment of the slab are any pair of drive rollers, the transmission device connected to the remaining drive rollers jointly provides pressure for the billet pulling resistance, and the free rollers that do not perform large reduction use hot billet pressing to reduce the slab; when the large reduction rollers for the sector segment of the slab are free rollers, the transmission device connected to the drive rollers jointly provides pressure for the billet pulling resistance.

[0047] The sector segment of this invention employs at least two pairs of drive rollers 1. During pressing, only one pair of pressing rollers is used for large pressing. Based on the change in solid fraction at the center of the billet, when single-roll pressing is performed using either drive roller 1 or free roller 2, the other drive rollers 1 provide corresponding pressure to provide a sufficiently large driving force and avoid billet stagnation.

[0048] As a preferred embodiment of the present invention, the formula for calculating the billet pulling resistance experienced by the large-reduction device of the slab sector during large reduction is: F=2σδ(2Rh-h 2 ) / R;

[0049] Where σ is the average deformation resistance, δ is the thickness of the billet, R is the radius of the pressing roll, h is half of the pressing amount, and F is the billet pulling resistance generated by the pressing of the pressing roll.

[0050] The following examples will further illustrate the present invention so that those skilled in the art can better understand its advantages and features.

[0051] Example 1

[0052] like Figures 1-3 As shown, the drive roller 1 and free roller 2 have a diameter of 400-450mm and adopt a segmented roller structure. This structure ensures minimal roller deformation during heavy reduction, resulting in better billet reduction. Each pair of reduction rollers can apply a reduction force of 200-300 tons. Each pair of reduction rollers has two reduction cylinders, and each pair can be individually reduced using displacement control or pressure control. Displacement sensors are installed inside the reduction cylinders, and proportional valves control the synchronization and position of the cylinders on both sides, controlling the roller gap of the heavy reduction rollers to achieve heavy reduction of the billet. Pressure sensors are installed in both the upper and lower chambers of the reduction cylinders, and pressure control is achieved through the proportional valves of the hydraulic system. Three pairs of transmission devices 3 are installed in the sector section.

[0053] In continuous casting, based on the billet thickness and steel grade, the billet solidification model calculates the solidification process of the billet according to factors such as molten steel conditions, crystallizer water volume, and secondary cooling water volume. Within the central solid fraction range of 0.3–0.8 for the billet, one pair of reduction rollers uses displacement control to apply a large reduction of 10–15 mm to the billet. Other free rollers 2, which do not undergo reduction, are reduced with a smaller hot billet pressure to prevent bulging. The other drive rollers 1 calculate the resulting drawing resistance based on whether the rollers that underwent large reduction have a transmission device 3, as well as the reduction amount and billet thickness. A certain pressure is then applied to obtain the corresponding frictional force, providing a sufficiently large driving force to assist in billet drawing.

[0054] This high-reduction sector employs five independently controlled high-reduction rollers. Even before the billet has fully solidified, a relatively small pressure can be used to apply a reduction of 10-15 mm, ensuring the improvement of the billet's central porosity. The smaller roller spacing allows for a wider range of casting speeds without causing bulging. The use of three pairs of drive rollers ensures that the sector provides sufficient driving force regardless of whether the rollers applying the high reduction are equipped with a transmission device 3.

[0055] As can be seen from the above specific embodiments, the slab sector large-scale pressing device and method provided by the present invention, by setting at least two pairs of driving rollers and free rollers set between adjacent driving rollers in the sector sector, and by setting each pair of pressing rollers with a separate pressing cylinder, allows each pair of pressing rollers to perform pressing independently. Since multiple pairs of pressing rollers work together, the roller diameter of the individual pressing roller can be reduced, and the roller distance between adjacent pressing rollers is small, effectively avoiding the occurrence of bulging. Pressing can be carried out within the solid fraction range. Since the slab is not fully solidified, the required pressing force is small, reducing the rigidity requirement of the sector sector frame. Unlike conventional sector sectors with only one pair of driving rollers, since the billet pulling resistance is large during large pressing, the present invention uses at least two pairs of driving rollers. When pressing, only one pair of pressing rollers is used for pressing. According to the change of solid fraction at the center of the slab, when using driving rollers or free rollers to perform single-roll pressing, the other driving rollers provide corresponding pressure to provide a sufficiently large driving force, effectively avoiding the occurrence of billet stagnation.

[0056] The slab sector large-short pressing apparatus and method 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 slab sector large-short pressing apparatus and method 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 large reduction device for a sector of a slab, characterized by, The utility model relates to a slab segment large reduction device, which comprises a reduction roller and a reduction control device. The reduction roller comprises at least two pairs of driving rollers and a pair of free rollers arranged between adjacent driving rollers; each pair of driving rollers comprises an upper driving roller and a lower driving roller, and each pair of free rollers comprises an upper free roller and a lower free roller; the roller diameter of the driving rollers is 400-450 mm, and the roller diameter of the free rollers is 400-450 mm; the distance between adjacent driving rollers and free rollers is 430-480 mm. Each pair of driving rollers is connected with a transmission device, which drives the upper driving roller and the lower driving roller to rotate. The reduction control device comprises a first reduction cylinder arranged on the upper driving roller and a second reduction cylinder arranged on the upper free roller. During the implementation of reduction, only one pair of reduction rollers is used for large reduction, and according to the change of the center solid phase rate of the cast slab, the driving rollers or the free rollers are used for single-roller reduction, and the other driving rollers give corresponding pressure. According to the interval position of the cast slab solid phase rate of 0.3-0.8, the drawing resistance of the slab segment large reduction device during large reduction is determined. According to the drawing resistance, the initial value of the transmission device is determined, and the large reduction of the slab segment is completed; when the reduction roller for implementing the large reduction of the slab segment is any pair of driving rollers, the transmission devices connected with the remaining driving rollers jointly provide pressure for the drawing resistance; when the reduction roller for implementing the large reduction of the slab segment is a free roller, the transmission devices connected with the driving rollers jointly provide pressure for the drawing resistance. The calculation formula of the drawing resistance of the slab segment large reduction device during large reduction is as follows: wherein σ is the average deformation resistance, δ is the thickness of the cast slab, R is the radius of the reduction roller, h is half of the reduction amount, and F is the drawing resistance generated by one pair of reduction rollers. ； 2. The slab segment large reduction device according to claim 1, wherein the reduction roller comprises three pairs of driving rollers and two pairs of free rollers.

3. The slab segment large reduction device according to claim 1, wherein the pressure value of each of the driving rollers and the free rollers is 200-300 tons.

4. The slab segment large reduction device according to claim 1, wherein the first reduction cylinder is arranged at both ends of each pair of driving rollers; and / or the second reduction cylinder is arranged at both ends of each pair of free rollers.

5. The slab segment large reduction device according to claim 1, wherein a first displacement sensor is arranged in the first reduction cylinder, and the moving displacement value of the upper driving roller obtained by the first displacement sensor is used to implement the reduction of the slab segment; and / or a second displacement sensor is arranged in the second reduction cylinder, and the moving displacement value of the upper free roller obtained by the second displacement sensor is used to implement the reduction of the slab segment.

6. The slab segment large reduction device according to claim 1 or 5, wherein ​ ​ ​ ​ ​ ​ ​ A first pressure sensor is arranged in the first press-down cylinder; the pressure value obtained by the first pressure sensor is used to press down the fan-shaped section of the cast blank by the upper drive roller; and / or A second pressure sensor is arranged in the second press-down cylinder; the pressure value obtained by the second pressure sensor is used to press down the fan-shaped section of the cast blank by the upper free roller.

Images