Crystallizer foot roller for eliminating casting blank narrow surface indentation, crystallizer and continuous casting machine

Abstract

The invention relates to the technical field of slab continuous casting, in particular to a crystallizer foot roller for eliminating casting blank narrow face indentations, a crystallizer and a continuous casting machine. The invention provides a crystallizer foot roller for eliminating casting blank narrow surface indentations, which is characterized in that the crystallizer foot roller comprises a segmented roller and a plurality of flat rollers, the segmented roller and the plurality of flat rollers are arranged at intervals to form a casting blank bearing surface, the segmented roller is arranged at a casting blank outlet of a crystallizer, and the segmented roller comprises a first roller body and a second roller body, the first roller body and the second roller body are connected through a connecting shaft, and the edges of the ends, close to the connecting shaft, of the first roller body and the second roller body are arranged to be fillets. A curve transition section is arranged on the edge of a roller body of the flat roller, extends in the axial direction of the roller body and is smoothly connected with the end face of the roller body and a roller face. According to the technical scheme, sharp contact between the narrow-face blank shell and the edge of the foot roller can be reduced, the industrial problem of corner indentation of a small-chamfer crystallizer casting blank is solved, and quality improvement of the small-chamfer casting blank is facilitated.

Description

Technical Field

[0001] This disclosure relates to the field of slab continuous casting technology, and in particular to a crystallizer foot roll, a crystallizer, and a continuous casting machine for eliminating narrow-face indentations on the slab. Background Technology

[0002] Producing billets with zero surface defects is the ultimate goal pursued in continuous casting technology. The crystallizer, as the heart of the continuous casting machine, is the crucial carrier for transforming molten steel into a solid billet shell. The flow field, heat transfer, and equipment precision of the crystallizer directly determine the quality of the billet. In existing technology, optimizing the chamfered crystallizer design, transforming the original large-chamfered crystallizer into a small-chamfered crystallizer, has improved both casting machine efficiency and billet quality. However, with the widespread application of small-chamfered crystallizers, the narrow faces of the produced small-chamfered billets exhibit indentations. Summary of the Invention

[0003] This disclosure aims to address at least one of the technical problems existing in the prior art or related technologies.

[0004] To this end, a first aspect of this disclosure provides a crystallizer foot roll for eliminating narrow-face indentations on cast billets, comprising a segmented roll and a plurality of flat rolls, wherein the segmented roll and the plurality of flat rolls are spaced apart to form a cast billet support surface, and the segmented roll is disposed at the cast billet outlet of the crystallizer, wherein the segmented roll comprises a first roll body and a second roll body, the first roll body and the second roll body are connected by a connecting shaft, and the edge of the first roll body and the second roll body near the connecting shaft is rounded; the edge of the flat roll body is provided with a curved transition section, the curved transition section extends along the axial direction of the roll body and smoothly connects the end face of the roll body and the roll surface.

[0005] In one possible implementation, the radius of the fillet is set to 3 mm to 6 mm.

[0006] In one possible implementation, the radius of the fillet is set to 4 mm.

[0007] In one feasible implementation, the axial extension length of the curve transition section is 30mm to 50mm, and the transition curve of the curve transition section is a continuous smooth surface.

[0008] In one feasible implementation, the cross-sectional profile of the curve transition section is a circular arc curve with a radius greater than or equal to 10 mm and less than or equal to 100 mm.

[0009] In one possible implementation, the number of flat rollers is set to three.

[0010] In one feasible implementation, the cross-sectional profile of the curved transition section is set such that the included angle θ of the tangent at the junction of the end face of the roller body and the roller surface is ≤15°.

[0011] In one feasible implementation, the spacing between the plurality of flat rollers is 1.2 to 1.5 times the thickness of the billet.

[0012] A second aspect of this disclosure provides a crystallizer including the crystallizer foot roll described above for eliminating narrow face indentations on the billet.

[0013] A third aspect of this disclosure provides a continuous casting machine including the crystallizer described above.

[0014] Compared with the prior art, this disclosure has at least the following beneficial effects: the edges of the first and second rollers near the connecting shaft are rounded, eliminating sharp contact between the segmented roller's diameter change position and the hot-cast billet, and eliminating the two indentations at the center of the narrow face; the edge of the flat roller is provided with a curved transition section, which extends along the roller body axially and smoothly connects the roller body end face and the roller surface. By setting the curved transition section to smooth the curve, the edge of the flat roller is rounded, thereby achieving curved surface contact between the foot roller and the billet shell during the contact process, eliminating the narrow face indentation defect caused by stress concentration due to the sharp edge of the foot roller. This disclosure can provide sufficient support for the narrow face billet shell and reduce the sharp contact between the narrow face billet shell and the edge of the foot roller, solving the industry problem of corner indentations in small-beveled crystallizer billets, and contributing to the improvement of the quality of small-beveled billets. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of exemplary embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 This is a schematic diagram of the segmented roller structure disclosed herein;

[0019] Figure 2 This is one of the structural schematic diagrams of the flat roller disclosed herein;

[0020] Figure 3 This is the second schematic diagram of the structure of the flat roller disclosed herein;

[0021] Figure 4 This is a schematic diagram of the arrangement structure of the segmented rollers and flat rollers disclosed in this paper.

[0022] in, Figures 1 to 4 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0023] 100 - Rounded corner; 200 - Curved transition section;

[0024] 1-Segmented roller; 11-First roller body; 12-Second roller body; 13-Connecting shaft; 2-Plain roller. Detailed Implementation

[0025] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0026] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0027] Currently, producing billets with zero surface defects is the ultimate goal pursued by continuous casting technology. The crystallizer, as the heart of the continuous casting machine, is a crucial carrier for transforming molten steel into a solid billet shell. The flow field, heat transfer, and equipment precision of the crystallizer directly determine the quality of the billet. Optimizing the chamfered crystallizer design in existing technology, transforming the original large-chamfered crystallizer into a small-chamfered crystallizer, has improved both casting machine efficiency and billet quality.

[0028] However, with the widespread application of small chamfered crystallizers, when the hot billet exits the crystallizer and enters the foot roll area, the narrow-faced foot roll supports the hot billet shell. When the narrow-faced billet shell passes the first chamfered foot roll, due to the segmented design of the chamfered foot roll, two indentations are generated at the center of the narrow face of the billet. After further optimization to a small chamfered crystallizer, on the basis of the original two indentations, since the thickness of the hot billet is greater than the length of the narrow-faced foot roll, the foot roll generates two indentations on the edge of the narrow face of the billet, which is very easy to form fine line defects on the edge during hot rolling.

[0029] For example, existing technologies use specific convex narrow-faced copper plates and convex foot rolls to produce concave billets, thereby reducing the width of edge black line defects during the widening rolling process. This solution has the following two drawbacks: 1. The combination of the convex copper plate and convex foot rolls makes it impossible to measure the arc alignment accuracy between the copper plate and the crystallizer foot rolls. Furthermore, this design easily causes wear on the copper plate, which is detrimental to maintaining the accuracy of the copper plate and foot rolls. 2. The produced concave billets are only suitable for widening rolling, resulting in a narrow process application window. When widening rolling is required, the uneven impact of the side-pressure width-fixing mill on the sharp corners of the billet easily deteriorates the edge quality of the coil during rolling. For example, utility model patent CN201201042Y provides a novel continuous casting crystallizer foot roller. This roller has an irregular shape, thicker in the middle and thinner at both ends, reducing the line contact length between the billet and the foot roller. This reduces the chance of water accumulation between the arc surface of the foot roller and the billet, eliminating the situation where the billet is soaked in water. This avoids additional forced cooling during casting, reduces uneven cooling and deformation of the billet, and improves the product qualification rate. The irregular continuous casting crystallizer foot roller provided by this utility model has a sharp right-angle transition between the center and the edge of the roller body, which easily presses deep indentations on the narrow surface of the billet. In severe cases, the center part of the roller body will press a depression defect on the narrow surface of the billet, seriously affecting the quality of the billet. For example, patent CN103128244 A provides a spindle foot roller for a slab continuous casting machine crystallizer. This foot roller includes a left foot roller body, a right foot roller body, and a middle foot roller body. The left and right foot roller bodies are cylindrical and symmetrically arranged, while the middle foot roller body is spindle-shaped. This effectively optimizes the support capacity of the narrow-face foot roller in the crystallizer, reduces bulging of the casting blank on the narrow face, and reduces edge cracks in the cast billet caused by bulging of the blank side, thus ensuring the quality of the cast billet. The spindle foot roller provided by this invention has a concave transition between its left and right portions and its middle portion. Because the cast billet exiting the crystallizer is in a hot state with low shell strength, when the narrow face of the cast billet passes through this foot roller, it is very easy to generate convex edges at the junction of the left and right portions and the middle portion, seriously affecting the quality of the cast billet.

[0030] Based on this, this disclosure provides a crystallizer foot roller for eliminating narrow-face indentations on cast billets. The edges of the first and second roller bodies near the connecting shaft are rounded, eliminating sharp contact between the segmented roller's diameter change position and the hot cast billet, and eliminating the two indentations at the center of the narrow face. The flat roller's edge has a curved transition section that extends axially along the roller body and smoothly connects the roller body end face and the roller surface. By setting the curved transition section to smooth the curve, the edge of the flat roller is rounded, thus achieving curved surface contact between the foot roller and the billet shell during contact, eliminating the narrow-face indentation defect caused by stress concentration due to the sharp edges of the foot roller. This disclosure provides sufficient support for the narrow-faced billet shell while reducing sharp contact between the narrow-faced billet shell and the edge of the foot roller, solving the industry problem of corner indentations on small-beveled crystallizer billets and contributing to improved quality of small-beveled billets.

[0031] The following detailed description uses specific examples to illustrate the crystallizer foot roller for eliminating narrow-face indentations on cast billets:

[0032] Reference Figures 1 to 4 As shown, the first aspect of this disclosure provides a crystallizer foot roller for eliminating narrow-face indentations on cast billets, including a segmented roller 1 and a plurality of flat rollers 2. The segmented roller 1 and the plurality of flat rollers 2 are spaced apart to form a cast billet support surface, and the segmented roller 1 is located at the cast billet outlet of the crystallizer. The segmented roller 1 includes a first roller body 11 and a second roller body 12, which are connected by a connecting shaft 13. The edge of the first roller body 11 and the second roller body 12 near the connecting shaft 13 is rounded 100. The edge of the flat roller 2 has a curved transition section 200, which extends along the roller body axial direction and smoothly connects the roller body end face and the roller surface.

[0033] The first and second rollers of this disclosure have rounded edges near the connecting shaft, eliminating sharp contact between the segmented roller's diameter change position and the hot-cast billet, and eliminating the two indentations at the center of the narrow face. The flat roller's edge has a curved transition section that extends axially along the roller body and smoothly connects the roller body end face and the roller surface. By setting a smooth curve in the curved transition section, the edge of the flat roller is rounded, thus achieving curved surface contact between the foot roller and the billet shell during the contact process, eliminating the narrow face indentation defect caused by stress concentration due to the sharp edge of the foot roller. This disclosure can provide sufficient support for the narrow face billet shell and reduce the sharp contact between the narrow face billet shell and the edge of the foot roller, solving the industry problem of corner indentations in small-beveled crystallizer billets, and contributing to the improvement of the quality of small-beveled billets.

[0034] Specifically, the segmented roller 1 and multiple flat rollers 2 of this disclosure are spaced apart to form a billet support surface, i.e., the foot roller passage of the crystallizer, used to support the billet produced by the crystallizer. Further, this disclosure specifically sets the number of flat rollers 2 to three. The first roller body 11 and the second roller body 12 of the segmented roller 1 of this disclosure have their diameter change points near the connecting shaft 13. The area with rounded corners and the transition between the first roller body 11 and the second roller body 12 should be a smooth transition without any chamfered edges, such as the "capsule" end. The rounded corners of this disclosure are intended to change the diameter change edge of the segmented roller from point contact and line contact with the billet to surface contact, thereby reducing the formation of indentations.

[0035] In some embodiments, the radius of the fillet 100 is set to 3 mm to 6 mm.

[0036] In this embodiment, the radius of the fillet 100 disclosed herein is set to 3mm to 6mm. This radius range can eliminate mechanical indentations (common in sharp transitions where R < 3mm) without affecting the dimensional accuracy of the narrow face of the billet due to an excessively large radius (> 6mm).

[0037] In some embodiments, the radius of the fillet 100 is set to 4 mm.

[0038] In this embodiment, the radius of the fillet 100 is set to 4mm. A 4mm fillet reduces the contact stress at the corner of the billet by 35%-40%, effectively dispersing the stress concentration caused by traditional right-angle structures and suppressing indentation at its source. This fillet size promotes uniform flow of the surface metal during solidification, avoiding surface tensile damage caused by excessive local resistance. The 4mm radius creates a smooth transition surface, reducing the coefficient of sliding friction between the roll surface and the billet compared to other sizes, significantly reducing the risk of mechanical scratches.

[0039] In some embodiments, the axial extension length of the curved transition section 200 is 30 mm to 50 mm, and the transition curve of the curved transition section 200 is a continuous smooth surface.

[0040] In this embodiment, a continuous smooth curved transition section with an axial extension length of 30-50mm, namely the curved transition section 200, is used to optimize stress distribution. The 30-50mm extension length enables a gradual transition of the contact pressure between the billet and the roll surface, reducing the stress peak and effectively avoiding surface microcracks caused by local stress concentration. The continuous smooth curved surface can also eliminate mechanical scratches caused by traditional right-angle transitions.

[0041] In some embodiments, the cross-sectional profile of the curved transition section 200 is a circular arc curve with a radius greater than or equal to 10 mm and less than or equal to 100 mm.

[0042] In this embodiment, the radius range effectively reduces the stress concentration factor, and the 100mm upper limit design avoids rigidity loss caused by an excessively large radius. The minimum radius of 10mm ensures that the surface roughness is within the required process range, and the arc curve reduces metal flow resistance by more than 25% compared to a right-angle transition. Furthermore, this radius range effectively disperses localized stress concentration caused by traditional right angles, suppressing indentation formation at its source. Specifically, the R50mm arc transition reduces the incidence of edge cracks by approximately 60% compared to a right-angle structure. The arc curve can evenly distribute heat exchange between the mold and the billet, reducing indentation defects caused by uneven shrinkage.

[0043] In some embodiments, the cross-sectional profile of the curved transition section 200 is set such that the included angle θ of the tangent at the junction of the roll body end face and the roll surface is ≤15°.

[0044] In this embodiment, a small-angle tangential transition (θ≤15°) reduces the stress concentration factor at the corner of the billet, significantly reducing local stress peaks caused by traditional right-angle transitions, thereby suppressing indentation formation. A smooth transition of θ≤15° reduces the flow resistance of the surface metal of the billet by more than 20%, preventing surface stretching indentations caused by flow stagnation.

[0045] In some embodiments, the spacing between the plurality of flat rollers 2 is 1.2 to 1.5 times the thickness of the billet.

[0046] In this embodiment, the spacing range improves the uniformity of strain distribution across the billet cross-section, effectively preventing edge cracks caused by excessive local deformation. A 1.5 times upper limit spacing, combined with segmented roll support, reduces the risk of billet bulging. A roll spacing of 1.2 times the thickness reduces the surface temperature fluctuation of the billet by 15-20°C, which is beneficial for maintaining the thermal stability of the secondary cooling zone.

[0047] A second aspect of this disclosure provides a crystallizer including the crystallizer foot rolls provided in the first aspect of this disclosure for eliminating narrow face indentations on the billet.

[0048] A third aspect of this disclosure provides a continuous casting machine, including the crystallizer provided in the second aspect of this disclosure.

[0049] In this disclosure, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise expressly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0050] In the description of this disclosure, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0051] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0052] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A crystallizer foot roller for eliminating narrow-face indentations on cast billets, characterized in that, It includes segmented rollers and multiple flat rollers, wherein the segmented rollers and the multiple flat rollers are spaced apart to form a billet support surface, and the segmented rollers are located at the billet outlet of the crystallizer. The segmented roller includes a first roller body and a second roller body, which are connected by a connecting shaft, and the edges of the first roller body and the second roller body near the connecting shaft are rounded. The edge of the flat roller body is provided with a curved transition section, which extends along the roller body axial direction and smoothly connects the roller body end face and the roller surface.

2. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The radius of the rounded corner is set to 3mm to 6mm.

3. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The radius of the fillet is set to 4mm.

4. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The axial extension length of the curve transition section is 30mm to 50mm, and the transition curve of the curve transition section is a continuous smooth surface.

5. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The cross-sectional profile of the curve transition section is a circular arc curve with a radius greater than or equal to 10 mm and less than or equal to 100 mm.

6. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The number of flat rollers is set to three.

7. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The cross-sectional profile of the curved transition section is set such that the included angle θ of the tangent at the connection between the end face of the roller body and the roller surface is ≤15°.

8. The crystallizer foot roller for eliminating narrow-face indentations on cast billets according to claim 1, characterized in that, The spacing between the plurality of flat rollers is 1.2 to 1.5 times the thickness of the billet.

9. A crystallizer, characterized in that, The crystallizer foot roll for eliminating narrow face indentations on the billet as described in any one of claims 1 to 8 above.

10. A continuous casting machine, characterized in that, Includes the crystallizer as described in claim 9.

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