Method for calculating and controlling taper of continuous casting slab width-adjusting chamfering crystallizer

Abstract

The invention relates to a method for calculating and controlling the taper of a continuous casting slab widening and chamfering crystallizer, and belongs to the technical field of metallurgical continuous casting methods. According to the technical scheme, the arc length of the chamfering crystallizer is calculated; calculating the side length of the chamfering crystallizer; calculating the own taper of the narrow side of the crystallizer according to the arc length and the side length of the chamfering crystallizer; controlling and optimizing the narrow-surface guide device of the crystallizer; the taper of the narrow-face chamfering copper plate is set to be 1.3-3.0%, and the taper deviation range is smaller than or equal to 0.5 mm. The method has the beneficial effects that through taper calculation and stable control of the continuous casting slab widening and chamfering crystallizer, the process quality requirement for the taper precision of the narrow face of the crystallizer is well guaranteed, the phenomenon that the taper of the crystallizer exceeds the standard in the continuous casting process is effectively avoided, and production and quality hidden dangers in the continuous casting process are eliminated.

Description

A method for calculating and controlling the taper of a crystallizer for adjusting the width and chamfering of continuously cast slabs. Technical Field

[0001] This invention relates to a method for calculating and controlling the taper of a crystallizer for adjusting the width and chamfering of continuously cast slabs, belonging to the technical field of metallurgical continuous casting methods. Background Technology

[0002] The slab crystallizer is a key piece of equipment in slab continuous casting production. A typical slab crystallizer consists of four copper plates arranged at right angles. Due to two-dimensional cooling, the shrinkage at the corners exceeds the compensation amount of the crystallizer's copper plate taper, resulting in large air gaps, especially at the wide corners. These air gaps account for over 80% of the total thermal resistance, further leading to excessively high temperatures in the corner areas, creating hotspots and generating significant transverse tensile stress within the plane of these areas. Conversely, the low corner temperatures (approximately 600℃~900℃) enter the third brittle zone, resulting in uneven temperature distribution across the entire slab shell surface. The introduction of chamfered crystallizers provides an effective method to address transverse crack defects at slab corners. Furthermore, user requirements for slab width vary, necessitating adjustments to the crystallizer width based on user needs. Therefore, the crystallizer must also possess an online thermal width adjustment function. Therefore, in order to improve the operating efficiency of continuous casting machines, solve the problem of transverse cracks at the corners of slabs, and meet the needs of various customers for multi-specification, small-batch production, a chamfered crystallizer with online thermal width adjustment function has emerged, which can significantly improve productivity and efficiency.

[0003] However, in continuous casting, excessive compression of the narrow edge of the chamfered crystallizer during hot width adjustment can cause defects such as cracks in the billet. It can also lead to excessive air gaps between the narrow edge and the billet, affecting the solidification and uniformity of the billet shell. In severe cases, this can cause serious production accidents such as bulging or sticking leaks. Especially for chamfered crystallizers, the corners of the billet cool less, making them more prone to longitudinal cracks and leaks. Therefore, online hot width adjustment of chamfered crystallizers has become a challenge and a taboo in the continuous casting industry. Furthermore, in continuous casting slab chamfered crystallizers, unstable control of the crystallizer's copper plate taper often leads to severe wear at the lower edge of the narrow-face copper plate, causing corner cracks and bulging of the narrow edge in the billet. In particular, transverse corner cracks account for more than 50% of all defects, and the application of microalloying technology exacerbates this problem. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calculating and controlling the taper of the crystallizer for adjusting the width and chamfering of continuously cast slabs. By calculating and stabilizing the taper of the crystallizer for adjusting the width and chamfering of continuously cast slabs, the process quality requirements for the accuracy of the narrow face taper of the crystallizer are well guaranteed. This effectively solves the problem of excessive taper of the crystallizer during continuous casting, eliminates potential production and quality hazards during continuous casting, and effectively solves the above-mentioned problems existing in the background technology.

[0005] The technical solution of this invention is: a method for calculating and controlling the taper of a continuous casting slab width adjustment and chamfering crystallizer, comprising the following steps:

[0006] (1) Calculate the arc length of the chamfered crystallizer;

[0007] (2) Calculate the side length of the chamfered crystallizer;

[0008] (3) Calculate the taper of the narrow side of the crystallizer based on the arc length and side length of the chamfered crystallizer;

[0009] (4) The narrow face guide device of the crystallizer is controlled and optimized. The narrow face guide device of the crystallizer includes a nut, a T-head bolt, an adjusting screw and a narrow face foot roller. When assembling the narrow face guide device of the crystallizer, the tightening torque of the nut and the T-head bolt reaches 100 N.m to achieve longitudinal positioning; the tightening torque of the adjusting screw reaches 100 N.m to achieve lateral positioning.

[0010] (5) The crystallizer narrow face guide device is assembled and fixed on the crystallizer narrow face insert. The crystallizer narrow face insert is connected to the width adjustment device. The crystallizer taper is adjusted by the operation of the width adjustment device. The taper of the narrow face chamfered copper plate is set to 1.3-3.0%, and the taper deviation range is ≤0.5mm.

[0011] In step (4), since the radius and chord length of the chamfered crystallizer are the same, the lengths of the arc segments are the same, and their values ​​are calculated as follows:

[0012] The chord length L and two radii of length R form an isosceles triangle. Assuming the angle between the two radii at the center is θ, the arc length S corresponding to the chord length L is 2πR×θ / 360.

[0013] In step (3), the length difference ΔL = arc length Y - line length a, the total chord length of the chamfer = W, and the self-taper of the narrow side of the crystallizer = ΔL / (ΔL+W)*100%.

[0014] In step (4), the T-head bolt has a diameter of M18 and is made of 40CrNiMo forging material, which is heat-treated to achieve a hardness of HB=340.

[0015] It also includes controlling the size of the siphon head to be 15mm smaller than the bottom of the crystallizer, ensuring that the size of the siphon head is smaller than the guide spacing, and preventing the siphon head from touching the narrow copper plate and guide during the casting process.

[0016] The beneficial effects of this invention are: by calculating and stabilizing the taper of the crystallizer for widening and chamfering the continuous casting slab, the process quality requirements for the taper accuracy of the narrow face of the crystallizer are well guaranteed, effectively solving the problem of excessive taper of the crystallizer during continuous casting and eliminating potential production and quality hazards during continuous casting. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the taper calculation data for the chamfered crystallizer of the present invention;

[0018] Figure 2 is a schematic diagram of solving the X value in the calculation of the side length of the chamfered crystallizer of the present invention;

[0019] Figure 3 is a three-dimensional structural schematic diagram of the narrow-face insert of the crystallizer of the present invention;

[0020] Figure 4 is a cross-sectional view of the narrow-face insert of the crystallizer of the present invention;

[0021] Figure 5 is a front view of the narrow-face guide device for the crystallizer of the present invention;

[0022] Figure 6 is a three-dimensional structural schematic diagram of the narrow-face guide device for the crystallizer of the present invention;

[0023] Figure 7 is a chamfering data diagram of the chamfered crystallizer 1 according to an embodiment of the present invention;

[0024] Figure 8 is a chamfering data diagram of the chamfered crystallizer 2 according to an embodiment of the present invention;

[0025] Figure 9 is a chamfering data diagram of the chamfered crystallizer 3 according to an embodiment of the present invention;

[0026] In the diagram: 1. Narrow copper plate; 2. Narrow back plate; 3. Support plate; 4. Holding block; 5. Clamping block; 6. Narrow insert of crystallizer; 7. Nut; 8. T-head bolt; 9. Adjusting screw; 10. Narrow foot roller. Detailed Implementation

[0027] To make the purpose, technical solutions, and advantages of the invention's embodiments clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only a small part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0028] A method for calculating and controlling the taper of a continuously cast slab width-adjusting and chamfering crystallizer includes the following steps:

[0029] (1) Calculate the arc length of the chamfered crystallizer;

[0030] (2) Calculate the side length of the chamfered crystallizer;

[0031] (3) Calculate the taper of the narrow side of the crystallizer based on the arc length and side length of the chamfered crystallizer;

[0032] (4) The narrow face guide device of the crystallizer is controlled and optimized. The narrow face guide device of the crystallizer includes a narrow face insert, a nut, a T-head bolt, an adjusting screw and a narrow face foot roller. When assembling the narrow face guide device of the crystallizer, the tightening torque of the nut and the T-head bolt reaches 100 N.m to achieve longitudinal positioning; the tightening torque of the adjusting screw reaches 100 N.m to achieve lateral positioning.

[0033] (5) The crystallizer narrow face guide device is assembled and fixed on the crystallizer narrow face insert. The crystallizer narrow face insert is connected to the width adjustment device. The crystallizer taper is adjusted by the operation of the width adjustment device. The taper of the narrow face chamfered copper plate is set to 1.3-3.0%, and the taper deviation range is ≤0.5mm.

[0034] In step (4), since the radius and chord length of the chamfered crystallizer are the same, the lengths of the arc segments are the same, and their values ​​are calculated as follows:

[0035] The chord length L and two radii of length R form an isosceles triangle. Assuming the angle between the two radii at the center is θ, the arc length S corresponding to the chord length L is 2πR×θ / 360.

[0036] In step (3), the length difference ΔL = arc length Y - line length a, the total chord length of the chamfer = W, and the self-taper of the narrow side of the crystallizer = ΔL / (ΔL+W)*100%.

[0037] In step (4), the T-head bolt has a diameter of M18 and is made of 40CrNiMo forging material, which is heat-treated to achieve a hardness of HB=340.

[0038] It also includes controlling the size of the siphon head to be 15mm smaller than the bottom of the crystallizer, ensuring that the size of the siphon head is smaller than the guide spacing, and preventing the siphon head from touching the narrow copper plate and guide during the casting process.

[0039] In practical applications, this invention includes the taper calculation and control optimization of the beveled crystallizer, comprising the following control steps:

[0040] 1. Calculation of the taper of the crystallizer for adjusting the width and chamfering of continuously cast slabs.

[0041] 1) Arc length calculation

[0042] Since the radius and chord length of the chamfered crystallizer are the same, the length of the arc segment is the same, as shown in Figure 1. Its value is calculated as follows:

[0043] The chord length L and two radii of length R form an isosceles triangle. Assuming the angle between the two radii at the center is θ, the arc length S corresponding to the chord length L is 2πR×θ / 360.

[0044] 2) Side length calculation

[0045] As shown in Figure 1, point A is the tangent point. We can first find the X value shown in the figure, and then solve for the side length b.

[0046] The solution diagram for X is shown in Figure 2.

[0047] Therefore, X = L*sin(θ / 2)

[0048] Side length c = (HX); Side length b = c / cosα°

[0049] Arc length Y = Arc length S + Side length b

[0050] The distance of the straight line segment from point A to the left surface, i.e., the line length 'a', is calculated as follows:

[0051] Line length a = X × ctgθ / 2 + b × tgɑ°

[0052] Length difference ΔL = arc length Y - line length a; total chord length of chamfer = W

[0053] The inherent taper of the narrow side of the crystallizer is then calculated as ΔL / (ΔL+W)*100%.

[0054] 2. Maintaining the stability of the taper of the crystallizer for adjusting the width and chamfering of continuously cast slabs.

[0055] The continuous casting slab width adjustment and chamfering crystallizer consists of a wide side, a narrow side, and four water tanks with copper plates. The inner arc-shaped water tank uses a clamping and releasing device composed of four lifting cylinders and disc springs to adjust its opening and closing. When clamping the narrow side copper plate, the disc springs apply force to tighten it. When releasing, oil is introduced into the cylinder on the rod side to loosen the wide side copper plate. This causes the narrow side insert of the crystallizer to move up and down a certain distance, adjusting the taper of the narrow side of the crystallizer.

[0056] The narrow face insert for the crystallizer is shown in Figures 3 and 4, and the narrow face guide device for the crystallizer is shown in Figures 5 and 6. The narrow face insert consists of a narrow copper plate 1, a narrow back plate 2, a support plate 3, a holding block 4, and a clamping block 5. The narrow copper plate 1 and the narrow back plate 2 are bolted together and then fixed to the support plate 3 using the clamping block 5 to form a single unit. The narrow face guide device is mounted and fixed on the holding block 4 of the narrow face of the crystallizer insert. The support plate 3 is connected to the width adjustment device, and the lugs on both sides of the holding block 4 are inserted into the guide grooves of the narrow face insert guide plate on the upper part of the crystallizer frame, allowing the narrow face insert to slide within the guide grooves. The crystallizer taper can be adjusted by the action of the width adjustment device.

[0057] In the narrow-face guide device of the crystallizer, insufficient tightening torque of nut 7 during crystallizer casting causes a gap between the mating surface of the narrow-face insert 6 and the narrow-face copper plate 1 (due to the influence of the guide's own weight). This causes the narrow-face insert 6 to rotate around the support plate 3 under the static pressure of molten steel, resulting in slight deformation of the T-head bolt 8 and causing the narrow-face insert 6 to deviate from its cone shape. Insufficient tightening torque between the adjusting screw 10, the support plate 3, and the narrow-face insert 6 also causes the narrow-face insert 6 to move outward a certain distance under the static pressure of molten steel after casting. This also causes slight deformation of the adjusting screw 10, resulting in the narrow-face insert 6 deviating from its cone shape. Therefore, this needs to be controlled and optimized.

[0058] When assembling the narrow face guide device of the crystallizer, the narrow face copper plate 1 is installed on the support plate 3 and the narrow face back plate 2. The tightening torque of the nut 7 and the T-head bolt 8 should reach 100 N.m to achieve longitudinal positioning of the narrow face guide device of the crystallizer; the tightening torque of the adjusting screw 10 should also reach 100 N.m to achieve lateral positioning of the narrow face guide device of the crystallizer.

[0059] Furthermore, in order to reduce the deformation of the T-head bolt 8 of the narrow face guide device of the crystallizer, the T-head bolt 8 has a diameter of M18 and is made of 40CrNiMo forgings, which are heat-treated to achieve a hardness of HB=300-340.

[0060] Furthermore, the size of the ingot head is controlled to be 10mm to 15mm smaller than the bottom opening of the crystallizer.

[0061] The investigation revealed that the narrow face taper of the crystallizer after the start of continuous casting was due to the dummy bar head being larger than the guide spacing. During the start of casting, when the dummy bar head was running, the sharp corner of the dummy bar head exerted a thrust on the narrow face guide, causing the taper of the narrow face to become smaller.

[0062] Example:

[0063] A certain factory uses an online adjustable chamfering crystallizer slab continuous casting machine with a 230*1600mm diameter. To effectively control the taper of the chamfering crystallizer, the following control method is adopted:

[0064] Calculation of taper of three types of chamfered crystallizers

[0065] 1. Arc length calculation

[0066] As can be seen from Figures 7 to 9, since the radius and chord length are the same, the length of the arc segment is the same, and its value is calculated as follows:

[0067] A chord length of 9.9 mm and two radii, each 38 mm long, form an isosceles triangle. Assuming the angle between the two radii at the center is θ, then sin(θ / 2) = 9.9 / (2 × 38). Solving for θ, we get θ = 14.9696°. Correspondingly, the arc length s corresponding to the 9.9 mm chord length is s = 2πr × θ / 360 = 2π × 38 × 14.9696 / 360 = 9.9282 mm. The total chord length of the chamfer is W = 92.5 mm.

[0068] 2. Side length calculation

[0069] As shown in Figures 1 and 2, point A is the tangent point. Therefore, we can first find the x value shown in the figure, and then solve for the side length.

[0070] The diagram below illustrates the solution for x.

[0071] Therefore, x = 9.9sin(θ / 2) = 9.9 × 9.9 / (2 × 38) = 1.2896 mm

[0072] (1) For chamfer 1

[0073] Side length b1 = (5.6 - 1.2896) / cos75° = 16.6541 mm

[0074] Arc length + side length = 9.9282 + 16.6541 = 26.5823 mm

[0075] The distance from point A to the straight line segment on the left side of the surface is calculated as follows:

[0076] 1.2896×ctgθ / 2+(5.6-1.2896)×tg75°

[0077] =1.2896×ctg14.9696° / 2+(5.6-1.2896)×tg75°=25.9045mm

[0078] ΔL = arc length - line length = 2 * (26.5823 - 25.9045) = 1.3556 mm

[0079] Therefore, the taper of the narrow side of the crystallizer is 1.3556 / (1.3556+92.5)*100% = 1.444%.

[0080] (2) For chamfer 2

[0081] Side length b2 = (6.8 - 1.2896) / cos70° = 16.1113 mm

[0082] Arc length + side length = 9.9282 + 16.1113 = 26.0395 mm

[0083] The distance from point A to the straight line segment on the left side of the surface is calculated as follows:

[0084] 1.2896×ctgθ / 2+(6.8-1.2896)×tg70°

[0085] =1.2896×ctg14.9696° / 2+(6.8-1.2896)×tg70°=24.9553mm

[0086] ΔL = arc length - line length = 2 * (26.0395 - 24.9553) = 2.1684 mm

[0087] Therefore, the taper of the narrow side of the crystallizer = 2.1684 / (2.1684 + 92.5) * 100% = 2.290%.

[0088] (3) For chamfer 3

[0089] Side length b3 = (8.6 - 1.2896) / cos65° = 17.2979 mm

[0090] Arc length + side length = 9.9282 + 17.2979 = 27.226 mm

[0091] The distance from point A to the straight line segment on the left side of the surface is calculated as follows:

[0092] 1.2896×ctgθ / 2+(8.6-1.2896)×tg65°

[0093] =1.2896×ctg14.9696° / 2+(8.6-1.2896)×tg65°=25.4928mm

[0094] ΔL = arc length - line length = 2 * (27.226 - 25.4928) = 3.4664 mm

[0095] Therefore, the taper of the narrow side of the crystallizer is 3.4664 / (3.4664+92.5)*100% = 3.612%.

[0096] When assembling the narrow-face guide device of the crystallizer, the tightening torque of nut 7 and T-head bolt 8 should reach 100 N·m to achieve longitudinal positioning of the guide device; the tightening torque of adjusting screw 10 should also reach 100 N·m to achieve lateral positioning of the guide device.

[0097] Furthermore, in order to reduce the deformation of the fixed narrow-face guide (T-head bolt), the T-head bolt 8 has a diameter of M18 and is made of 40CrNiMo forgings, which are heat-treated to achieve a hardness of HB=340.

[0098] Furthermore, the size of the dummy bar head is controlled to be 15mm smaller than the bottom opening of the crystallizer, ensuring that the size of the dummy bar head is smaller than the guide spacing, so that the dummy bar head does not touch the narrow copper plate and guide during the casting process.

[0099] After adopting the above-mentioned control method of the present invention, the slab width adjustment crystallizer corner gap is ≤0.3mm, the width adjustment accuracy is ≤0.15mm, and the crystallizer taper adjustment accuracy is ≤0.5mm. This effectively ensures the process quality requirements of the crystallizer corner gap and taper accuracy, effectively solves the phenomenon of excessive crystallizer corner gap and taper during continuous casting, eliminates potential production and quality hazards during continuous casting, and has never caused equipment accidents that affect quality and production operation.

Claims

1. A method for calculating and controlling the taper of a continuously cast slab width-adjusting and chamfering crystallizer, characterized in that... The process includes the following steps: (1) Calculate the arc length of the chamfered crystallizer; (2) Calculate the side length of the chamfered crystallizer; (3) Calculate the self-taper of the narrow side of the crystallizer based on the arc length and side length of the chamfered crystallizer; (4) Optimize the control of the narrow face guide device of the crystallizer. The narrow face guide device of the crystallizer includes a nut, a T-head bolt, an adjusting screw and a narrow face foot roller. When assembling the narrow face guide device of the crystallizer, the tightening torque of the nut and the T-head bolt reaches 100 N·m to achieve longitudinal positioning; the tightening torque of the adjusting screw reaches 100 N·m to achieve transverse positioning; (5) The narrow face guide device of the crystallizer is assembled and fixed on the narrow face insert of the crystallizer. The narrow face insert of the crystallizer is connected to the width adjustment device. The crystallizer taper is adjusted by the action of the width adjustment device. The taper of the narrow face chamfered copper plate is set to 1.3-3.0%, and the taper deviation range is ≤0.5mm.

2. The method for calculating and controlling the taper of the continuous casting slab width adjustment and chamfering crystallizer according to claim 1, characterized in that: In step (4), the radius and chord length of the chamfered crystallizer are the same, so the length of the arc segment is the same. The value is calculated as follows: the chord length L and the two radii of length R form an isosceles triangle. Assuming that the angle between the two radii at the center of the circle is θ, the arc length S corresponding to the chord length L is 2πR×θ / 360.

3. The method for calculating and controlling the taper of a continuous casting slab width adjustment and chamfering crystallizer according to claim 1, characterized in that: In step (3), the length difference ΔL = arc length Y - line length a, the total chord length of the chamfer = W, and the self-taper of the narrow side of the crystallizer = ΔL / (ΔL+W)*100%.

4. The method for calculating and controlling the taper of a continuous casting slab width adjustment and chamfering crystallizer according to claim 1, characterized in that: In step (4), the T-head bolt has a diameter of M18 and is made of 40CrNiMo forging material, which is heat-treated to achieve a hardness of HB=340.

5. The method for calculating and controlling the taper of a continuous casting slab width adjustment and chamfering crystallizer according to claim 1, characterized in that: It also includes controlling the size of the siphon head to be 15mm smaller than the bottom of the crystallizer, ensuring that the size of the siphon head is smaller than the guide spacing, and preventing the siphon head from touching the narrow copper plate and guide during the casting process.

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