Submersed nozzle for thin slab continuous casting

Abstract

The invention relates to a sheet billet continuous casting submersed nozzle which comprises a nozzle body, a flow dividing body and a flow guiding body. Molten metal channels which are symmetrically through in the axial direction are arranged in the nozzle body, and the nozzle body is composed of a molten metal inflow section, an expansion section and an outflow section which are sequentially connected from top to bottom. The flow dividing body comprises a central flow dividing body with a side surface groove and a pair of axisymmetric outer side flow dividing bodies which are arranged in the outflow section, so that five dispersion liquid outflow ports are formed in the water gap; the flow guide bodies are a pair of axially symmetrical flow guide bodies arranged in the outflow section and automatically guide and distribute the flow quantity of molten metal flowing out of the main outflow channel and the outer auxiliary outflow channel. Through the mutual matching effect of the flow dividing body and the flow guiding body which are arranged in the outflow section of the water gap, the water gap can meet the requirement of producing high-quality casting blanks under the condition of different metal liquid flows at high and low pulling speeds when an MCCR thin slab continuous casting machine is used for casting large-section and small-section casting blanks.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin slab continuous casting, in particular to a MCCR thin slab continuous casting production of large and small section billets and a flexible and universal submerged entry nozzle at high and low casting speed. BACKGROUND

[0002] In the continuous casting of molten metal (especially molten steel), the molten metal with a certain superheat needs to be poured from the tundish to the mold through the submerged entry nozzle (SEN) made of refractory material to realize protective pouring and prevent the secondary oxidation of the molten metal. Meanwhile, the structure and size of the submerged entry nozzle (SEN) directly affect the flow field and temperature field of the molten metal flowing into the mold, and further affect the internal and external quality of the continuous casting billet and the efficiency of the continuous casting production.

[0003] The multi-mode continuous casting and rolling production line (MCCR) is a new generation of thin slab continuous casting and rolling production line. The section width of the MCCR continuous casting billet can be from 900 mm to 1500 mm or more, the thickness of the section of the continuous casting billet reaches 110 mm or more, and the maximum casting speed of the continuous casting production can reach 5.5 m / min or more. On the one hand, the MCCR thin slab continuous casting machine requires stable and high-quality production at a casting speed of 5.0 m / min (metal flux of 6 tons / min) or more in the normal production process of the normal casting, and stable and high-quality production at a lower casting speed (such as 3.5 m / min) and lower metal flux for a period of time in a casting. On the other hand, the MCCR thin slab continuous casting machine selects the production of continuous casting billets with a section width of from 900 mm to 1500 mm or more. Therefore, the metal flux flowing through the submerged entry nozzle changes greatly in the case of different sizes of the section of the continuous casting billet and different casting speeds. The actual requirement is that the submerged entry nozzle can adapt to the production of large and small section continuous casting billets of the MCCR thin slab continuous casting machine, and ensure the stability of the metal liquid level in the funnel-shaped mold of the thin slab continuous casting machine, small amplitude of liquid level fluctuation, and no "liquid level slag rolling" phenomenon at different conditions of high and low casting speed or high and low metal flux. At the same time, the temperature of the metal liquid level is relatively high, which is beneficial to the melting of the protective slag and the play of the metallurgical function, and no "liquid level cold steel" phenomenon occurs. Finally, the purpose of stable and continuous casting production of internal and external high-quality continuous casting billets is achieved.

[0004] At present, only two submerged entry nozzles with different structures and sizes can be used in actual production to adapt to the casting production of continuous casting billets with different sizes, which brings difficulties and waste to the actual continuous casting production organization. The two submerged entry nozzles used in the existing MCCR thin slab continuous casting are as follows Figure 9 andFigure 10 As shown, they are applied in MCCR thin slab continuous casting machine production, the existing technology 1 Figure 9 As shown) is applied in the continuous casting production of the slab with small section width (900mm-1350mm), which is not suitable for the stable production of the continuous casting slab with section width above 1350mm at high casting speed; the existing technology 2 Figure 10 As shown) is applied in the continuous casting production of the slab with large section (greater than 1350mm), which is not suitable for the stable production of the continuous casting slab with section width below 1350mm at low casting speed. The two kinds of water gaps cause the excessive fluctuation of the metal liquid surface in the crystallizer or the local temperature of the metal liquid in the crystallizer is too low to cause the cold shutdown and other problems during the continuous casting production of the slab with the section width and the corresponding casting speed, which cannot meet the requirements of the high-quality and stable continuous casting production. Therefore, the actual production needs to provide a structure size of the submerged nozzle (SEN) to meet the requirements of the flexible and universal continuous casting production of the high-quality slab under the different process conditions of the large and small section slabs and the high and low casting speeds. SUMMARY

[0005] The present application is aimed at the problems existing in the prior art, and provides a submerged nozzle which can be universally used in the production of the large and small section slabs and the high and low casting speeds of the MCCR thin slab continuous casting machine, and can make the metal liquid in the crystallizer have better dispersion, stable flow and temperature distribution, so as to meet the requirements of the stable production of the high-quality slab under various process conditions by using a single submerged nozzle in the MCCR thin slab continuous casting. In order to achieve the purpose, the present application is realized by adopting the specific configuration of the metal liquid passage in the nozzle and the technical scheme of the passage cross-sectional area.

[0006] A thin slab continuous casting submerged nozzle, comprising a nozzle body, a flow divider and a flow guide; a metal liquid passage is arranged in the nozzle body and penetrates along the central vertical axis direction, the cross section perpendicular to the axis is symmetrical, and the metal liquid passage has an inlet; the nozzle body is composed of an inflow section, an expansion section and an outflow section connected in sequence from top to bottom, and the metal liquid passages in the sections are connected smoothly, and the nozzle of the present application is characterized in that: a central flow divider and a pair of axisymmetric outer flow dividers and a pair of axisymmetric flow guides are arranged in the outflow section of the nozzle body, so that the end face of the outflow section of the metal liquid passage in the nozzle forms five dispersion outlets; wherein:

[0007] The central flow divider is arranged on the bottom central axis in the outflow section of the nozzle body, the central flow divider has a top surface and a bottom surface, a pair of axisymmetric side surfaces and a central outflow passage, the top surface and the bottom surface of the central flow divider are both horizontal surfaces, and a pair of axisymmetric grooves are arranged on the two side surfaces of the central flow divider;

[0008] The pair of axisymmetric outer side flow bodies are located between the central flow body and the corresponding nozzle side walls on both sides, and have their arc top surfaces, inner side flow inclined planes, outer side flow inclined planes and lower inclined bottom surfaces; the inner side flow inclined planes of the outer side flow bodies and the side surfaces of the central flow bodies on the same side and the wide surfaces of the inner passages of the nozzle outflow sections constitute the main outflow passages of the nozzle; the outer side flow inclined planes of the outer side flow bodies and the side arc surfaces of the central flow bodies on the same side located near the metal liquid passages of the nozzle outlets in the expansion sections and the wide surfaces of the inner passages of the nozzle outflow sections constitute the two auxiliary outflow passages of the nozzle on the outer side.

[0009] The pair of axisymmetric flow guide bodies are arranged at the upper part of the outflow section of the nozzle body, and have their top surfaces, bottom surfaces, outer side inclined planes and inner side inclined planes; the top and bottom surfaces of the flow guide bodies are horizontal planes, and the inner side inclined plane and the outer side inclined plane of each flow guide body are parallel to each other; the inclination angles of the inner side inclined plane and the outer side inclined plane of the flow guide body are the same as the flow guide inclination angle of the inner side flow inclined plane of the outer side flow body on the same side.

[0010] Further, the two side surfaces of the central flow body are provided with a pair of axisymmetric groove bottom surfaces, the depth of which decreases from top to bottom; the upper part of the groove bottom surface is an arc surface, which is connected to the flow inclined plane of the lower part; the flow guide inclination angle of the flow inclined plane of the middle and lower part of the groove on the side surface of the central flow body is from 5 degrees and including 5 degrees to 8 degrees and including 8 degrees; the groove width provided on the side surface of the central flow body is 1 / 3-3 / 4 of the maximum width of the cross section of the metal liquid passage in the outflow section of the nozzle body.

[0011] Further, the width of the bottom surface of the central flow body is 70 mm and including 70 mm to 80 mm and including 80 mm; the maximum width of the top surface of the central flow body is 100% and including 100% to 150% and including 150% of the width of the bottom surface of the central flow body; the height of the central flow body is greater than 1 / 2 of the distance between the bottom surface of the flow guide body and the bottom end surface of the nozzle body, and is less than 2 / 5 of the length of the outflow section of the nozzle body.

[0012] Further, the flow guide inclination angle of the outer side flow inclined plane of the pair of axisymmetric outer side flow bodies is from 25 degrees and including 25 degrees to 35 degrees and including 35 degrees, and the flow guide inclination angle of the inner side flow inclined plane is from 12 degrees and including 12 degrees to 18 degrees and including 18 degrees; the lower inclined bottom surface of the outer side flow body constitutes part of the bottom outer side inclined end surface of the outflow section of the nozzle body, and the horizontal inclination angle of the end surface is from 40 degrees and including 40 degrees to 50 degrees and including 50 degrees.

[0013] Further, the curvature radius of the arc top surface of the pair of axisymmetric outer side flow bodies is from 10 mm to 15 mm; the minimum distance between the pair of axisymmetric outer side flow bodies is 70% to 80% of the maximum length of the cross section of the metal liquid passage in the outlet section of the nozzle body; and the distance from the highest point of the arc top surface of the outer side flow body to the bottom end surface of the nozzle body is 80% to 90% of the length of the outlet section of the nozzle body.

[0014] Further, the minimum distance between the pair of axisymmetric flow bodies is 25% to 30% of the maximum length of the cross section of the metal liquid passage in the outlet section of the nozzle body, and is less than 50% of the minimum distance between the pair of axisymmetric outer side flow bodies; and the length of the outer side inclined plane of the flow body is greater than or equal to the length of the bottom surface, and is less than 150% of the length of the bottom surface.

[0015] Further, the height position of the top surface of the flow body is 0 to 10 mm lower than the upper edge of the auxiliary outlet passage hole, i.e., the inlet position of the outlet section of the nozzle body, and is higher than the highest point position of the arc top surface of the outer side flow body; and the distance from the bottom surface of the flow body to the bottom end surface of the nozzle body is 65% to 70% of the length of the outlet section of the nozzle body, and is lower than the highest point position of the arc top surface of the outer side flow body.

[0016] Further, the horizontal top surface and the inner side inclined plane of the pair of axisymmetric flow bodies can be connected by a small arc surface or a small vertical surface.

[0017] Further, the metal liquid passage in the inlet section of the nozzle body is a circular passage with a bowl-shaped inlet, the diameter of the circular cross section at the inlet is 80 mm to 95 mm, the circular cross sectional area at the inlet is 190% to 210% of the circular cross sectional area at the outlet, and the length of the inlet section is 1 / 8 to 1 / 7 of the total length of the nozzle body.

[0018] Further, the inlet of the metal liquid passage in the expansion section of the nozzle body is consistent with the outlet of the metal liquid passage in the inlet section, then the cross section of the metal liquid passage in the expansion section is a flat cross section, and the cross sectional area gradually increases, and is controlled by three cross sectional dimensions, the cross sectional area at the outlet of the metal liquid passage in the expansion section is 255% to 265% of the cross sectional area at the inlet; and the length of the expansion section is 5 / 7 to 7 / 9 of the total length of the nozzle body.

[0019] Further, the maximum length of the cross section of the metal liquid passage in the outflow section of the nozzle body is 360-400 mm, the length of the middle horizontal end surface of the bottom of the outflow section of the nozzle body is 50-60% of the maximum length of the cross section of the metal liquid passage in the outflow section of the nozzle body, and the length of the outflow section of the nozzle body is 1 / 9-1 / 8 of the total length of the nozzle body.

[0020] Further, the basic wall thickness of the refractory material of the nozzle body is 25-40 mm, the wall thickness of the material of the side surface of the nozzle body near the outlet of the expansion section gradually decreases along the curvature radius of the side expansion surface, the wall thickness of the material of the wide surface of the outflow section of the nozzle body gradually decreases to 2 / 3 of the wall thickness at the inlet, and the total length of the nozzle body is the sum of the lengths of the three sections (the inflow section, the expansion section and the outflow section).

[0021] Compared with the prior art, the thin slab continuous casting submerged nozzle has the following beneficial effects:

[0022] The thin slab continuous casting submerged nozzle can better automatically disperse and distribute the metal liquid, the metal liquid in the crystallizer has more reasonable flow and better temperature distribution in the crystallizer when the thin slab continuous casting machine produces different large and small section cast slabs and different casting speeds, the demand for stably producing high-quality continuous cast slabs under various process conditions can be met by using one kind of submerged nozzle, and the continuous casting production organization is facilitated and the production efficiency is improved.

[0023] The thin slab continuous casting submerged nozzle can stably produce cast slabs with full-size range sections at a casting speed of 3.0-5.0 m / min or above, and the occurrence of the "liquid surface slag rolling" phenomenon in the crystallizer is avoided.

[0024] The thin slab continuous casting submerged nozzle can stably produce cast slabs with full-size range sections, and the occurrence of the "hard as a rock" phenomenon in the crystallizer is avoided at various casting speeds. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application, and do not constitute improper limitations on the present application. In the drawings:

[0026] ATTACHMENT Figure 1 is a schematic view of the front central vertical section of the nozzle described in the present application;

[0027] ATTACHMENT Figure 2 is a schematic view of the side central vertical section of the nozzle described in the present application;

[0028] ATTACHMENT Figure 3This is an enlarged perspective view of the center flow distribution of the water inlet described in this invention;

[0029] Appendix Figure 4 This is a detailed view of the outflow section of the sprue described in this invention;

[0030] Appendix Figure 5 This is a dimensioned view of the outflow section structure of the water inlet described in this invention;

[0031] Appendix Figure 6 The water inlet described in this invention is... Figure 1 Horizontal cross-section at point AA;

[0032] Appendix Figure 7 The water inlet described in this invention is... Figure 1 Horizontal cross-section at point BB;

[0033] Appendix Figure 8 The water inlet described in this invention is... Figure 1 Horizontal cross-section at point C;

[0034] Appendix Figure 9 This is a schematic diagram of the submerged sprue for thin slabs in prior art 1;

[0035] Appendix Figure 10 This is a schematic diagram of the submerged sprue for thin slabs in prior art 2;

[0036] Appendix Figure 11 It is attached Figure 9 A comparison chart of velocity simulation data between the immersion nozzle of prior art 1 and the nozzle of the present invention is shown.

[0037] Appendix Figure 12 It is attached Figure 10 The diagram shows a comparison of the velocity simulation data between the immersion nozzle of prior art 2 and the nozzle described in this invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] In the diagram: 1. Inlet body 2. Inflow section 3. Expansion section 4. Outflow section 5. Central distributor 6. Outer distributor 7. Guide fluid 11. Middle end face of the inlet body 22. Outer inclined end face of the bottom of the inlet body 33. Main outlet channel of the inlet 44. Auxiliary outlet channel of the inlet 51. Top surface of the central distributor 52. Bottom surface of the groove of the central distributor 61. Inner guide inclined plane of the outer distributor 62. Outer guide inclined plane of the outer distributor 63. Top surface of the guide arc of the outer distributor 71. Inner inclined plane of the guide fluid 72. Outer inclined plane of the guide fluid 73. Top surface of the guide fluid 74. Bottom surface of the guide fluid O. Central vertical axis of the inlet body Detailed Implementation

[0040] To make the objectives, technical solutions, and technical effects of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0041] like Figures 1-8 As shown, the thin slab continuous casting submerged entry nozzle of the present invention includes a nozzle body 1, a central distribution fluid 5, an outer distribution fluid 6, and a guide fluid 7; the nozzle body 1 is composed of an inflow section 2, an expansion section 3, and an outflow section 4 connected sequentially from top to bottom; the nozzle body 1 is provided with a molten metal channel running through the vertical central axis O, the cross-section of the molten metal channel is symmetrical, and the molten metal channels are smoothly connected; the molten metal channel in the nozzle body 1 has one inlet and five outlets.

[0042] The molten metal channel in the inflow section 2 is a circular channel with a bowl-shaped inlet. The diameter of the circular cross-section of the outlet of the molten metal channel in the inflow section 2 is set to 90 mm, or it can be from 80 mm to 90 mm, or from 85 mm to 95 mm. The circular cross-sectional area at its inlet is 198% of the circular cross-sectional area at its outlet. The length H1 of the circular cross-section inflow section 2 is set to 165 mm, or it is 1 / 8 to 1 / 7 of the total length of the sprue body 1.

[0043] The inlet of the molten metal channel in the expansion section 3 is the same as the circular outlet of the molten metal channel in the inflow section 2, with the same cross-section. Then, there is a flat cross-section channel whose cross-section gradually increases in length and decreases in width. The flat cross-section is basically a rectangular surface with semi-circular ends, and its area gradually increases, controlled by the dimensions of three cross-sections AA, BB, and CC. In one embodiment, the distance between the AA cross-section and the inlet of the molten metal channel in the expansion section 3 is 420 mm, or can range from 400 mm to 430 mm; the distance between the AA cross-section and the BB cross-section is 310 mm, or can range from 300 mm to 320 mm; the distance between the BB cross-section and the CC cross-section is 250 mm, or can range from 240 mm to 260 mm; the length H2 of the expansion section 3 is 980 mm, or 5 / 7 to 7 / 9 of the total length of the nozzle body 1.

[0044] Figures 6-8 yes Figures 1-2The A-A, B-B and C-C cross-sectional views of the expanding section 3 of the nozzle body 1 of the present application are shown in the figure. In one embodiment, the ratio of the inner length a11 to the inner width b11 of the A-A cross-section is set to 2.4, or can be from 2.3 to 2.5; the metal liquid passage at the A-A cross-sectional area is 140% of the cross-sectional area at the inlet of the metal liquid passage in the expanding section 3, or from 135% to 145%; the ratio of the inner length a21 to the inner width b21 of the B-B cross-section can be set to 4.85, from 4.75 to 4.95; the metal liquid passage at the B-B cross-sectional area is 180% of the cross-sectional area at the inlet of the metal liquid passage in the expanding section 3, or from 170% to 185%; the ratio of the inner length a31 to the inner width b31 of the C-C cross-section can be set to 8.65, from 8.5 to 8.9; the metal liquid passage at the C-C cross-sectional area is 260% of the cross-sectional area at the inlet of the metal liquid passage in the expanding section 3, or from 255% to 265%; the outer length a12, a22 and the outer width b12, b22, b32 of each cross-section are the required inner length and inner width plus 2 times the basic wall thickness of the nozzle body material, respectively; the inner width b31 of the C-C cross-section is 40 mm, or from 30 mm to 50 mm; the inner length of the C-C cross-section is the same as the outer length a31, which is 385 mm, or from 360 mm to 400 mm.

[0045] The channel in the outflow section 4 is a flat cross-section, and the inlet is the outlet of the expanding section 3; the maximum length of the cross-section of the metal liquid passage in the outflow section 4 is a31; the maximum width of the cross-section of the metal liquid passage in the outflow section 4 is b31; the length H3 of the outflow section 4 is 145 mm, or 1 / 9 to 1 / 8 of the total length of the nozzle body.

[0046] The outflow section 4 of the nozzle body 1 is provided with a central flow divider 5 and a pair of axisymmetric outer flow dividers 6 and a pair of axisymmetric flow guides 7, so that the end face of the outflow section of the metal liquid passage in the nozzle forms five dispersed outlets; wherein:

[0047] The central flow divider 5 is arranged on the bottom central axis of the outflow section 4 of the nozzle body 1, and the central flow divider 5 has an upper top surface 51 and a lower bottom surface, a pair of axisymmetric side surfaces of the central flow divider 5 and a vertical circular hole central outflow channel; the upper top surface 51 and the lower bottom surface of the central flow divider are both horizontal surfaces, and a pair of axisymmetric grooves are arranged on the two side surfaces of the central flow divider.

[0048] In one embodiment, the depth of the groove bottom surface 52 is from deep to shallow from top to bottom, the upper part of the groove bottom surface 52 is a circular arc surface with a radius of 5mm-10mm, and the middle and lower part of the groove bottom surface 52 is a flow guide inclined plane with a flow guide inclination angle γ of 6 degrees; the width of the groove is 20mm, or 1 / 3-3 / 4 of the value of b31.

[0049] The width b of the bottom surface of the center flow distributor 5 is 70mm and includes 70mm to 80mm and includes 80mm; the maximum width a of the top surface 51 of the center flow distributor 5 is 80mm, or 100% of the value of b and includes 100% to 150% and includes 150%; the height h1 of the center flow distributor 5 can be 60mm, or 1 / 2 of the value of h2 to 2 / 5 of H3.

[0050] A vertical circular hole center flow out passage is provided in the center flow distributor 5 with a diameter of 19mm, or from 15 to 25mm; the lower bottom surface of the center flow distributor 5 constitutes the center part of the middle end surface 11 of the nozzle body 1.

[0051] The pair of axisymmetric outer side flow distributors 6 are arranged between the center flow distributor 5 and the side walls of the corresponding nozzle bodies 1 on both sides, the outer side flow distributor 6 has a flow guide circular arc top surface 63, an inner side flow guide inclined plane 61, an outer side flow guide inclined plane 62, and a lower inclined bottom surface; the inner side flow guide inclined plane 61 of the outer side flow distributor 6 and the side surface of the same side center flow distributor 5 and the wide surface of the outflow section inner passage constitute the main flow out passage 33 of the nozzle; the outer side flow guide inclined plane 62 of the outer side flow distributor 6 and the side arc surface of the metal liquid passage near the outlet of the expansion section 3 and the wide surface of the outflow section 4 inner passage constitute the two outer side auxiliary flow out passages 44 of the nozzle.

[0052] In one embodiment, the included angle between the outer side flow guide inclined plane 62 of the outer side flow distributor 6 and the center vertical axis O, i.e. the flow guide inclination angle α, is 30 degrees, or 25-35 degrees; the flow guide inclination angle β of the inner side flow guide inclined plane 61 of the outer side flow distributor 6 is 15 degrees, or 12-18 degrees; the curvature radius r of the flow guide circular arc top surface 63 of the outer side flow distributor 6 is 13mm, or 10-15mm; the lower inclined bottom surface of the outer side flow distributor 6 constitutes part of the bottom outer side inclined end surface 22 of the outflow section 4 of the nozzle body 1, the horizontal inclination angle θ of the bottom outer side inclined end surface 22 is 45 degrees, or 40-50 degrees; the minimum distance d of the pair of axisymmetric outer side flow distributors 6 is 285mm, or 70%-80% of a31; the distance h3 from the highest point of the flow guide circular arc top surface 63 of the outer side flow distributor 6 to the bottom end surface 11 of the nozzle body 1 is 120mm, or 80-90% of the value of H3.

[0053] The pair of axisymmetric flow guides 7 are arranged at the upper part of the outlet section 4 of the shroud 1, and have inner inclined planes 71, outer inclined planes 72, top planes 73 and bottom planes 74; the top plane 73 of each flow guide and the bottom plane 74 of the flow guide are horizontal planes.

[0054] In one embodiment, the minimum distance e between the pair of axisymmetric flow guides 7 is 105 mm, or 25-30% of the value of a31, and less than 50% of the value of d; the length of the outer inclined plane 72 of the flow guide 7 is 40 mm, or from 35 mm to 50 mm; the length of the bottom plane 74 of the flow guide 7 can be 33 mm, or from 30 mm to 40 mm; the height position of the top plane 73 of the flow guide 7 is 5 mm lower than the upper edge of the auxiliary outlet passage hole, i.e. the inlet position of the outlet section 4 of the shroud 1, or from 0 mm to 10 mm, and higher than the highest point position of the arc top plane of the outer flow guide; the distance h2 between the bottom plane 74 of the flow guide 7 and the bottom end surface 11 of the shroud 1 is 100 mm, or 65-70% of the value of H3, and lower than the highest point position of the arc top plane 63 of the outer flow guide 6; the length B of the bottom middle horizontal end surface 11 of the outlet section 4 of the shroud 1 is 210 mm, or 50-60% of the value of a31.

[0055] The included angle between the inner inclined plane 71 and the outer inclined plane 72 of the flow guide 7 and the central vertical axis O is the same as the flow guide inclined angle β of the inner inclined plane 61 of the same side of the outer flow guide 6.

[0056] In one embodiment, the connection between the top plane 73 and the inner inclined plane 71 of the pair of axisymmetric flow guides 7 uses a small arc surface, and the radius can be 8 mm, or from 5 mm to 10 mm; or a small vertical surface can be used for connection, and the vertical length is 8 mm, or from 5 mm to 10 mm.

[0057] In one embodiment, the material wall thickness of the shroud 1 is 30 mm, the wall thickness of the narrow surface of the shroud 1 near the outlet of the expansion section 3 gradually thins to zero according to the curvature radius R of the side expansion arc surface, the material wall thickness of the wide surface of the outlet section 4 of the shroud 1 gradually thins to 20 mm, and the total length of the shroud 1 is 1285 mm, or from 1270 mm to 1300 mm according to the continuous casting equipment.

[0058] The beneficial effects of the thin slab submerged shroud according to the present application are further illustrated by the flow field simulation test of the embodiment.

[0059] Figure 11A comparison chart of the velocity of the molten metal in the width direction of the horizontal section of the crystallizer at the outlet of the shroud for the application of the prior art 1 and the shroud of the present application when casting a large-section billet at a high casting speed in MCCR continuous casting.

[0060] As shown in the figure, the velocity distribution of the molten metal in the width direction of the crystallizer at the outlet of the shroud of the present application (the data indicated by the dotted line) is relatively more uniform and dispersed, and the maximum velocity thereof is reduced by about 30% than the maximum velocity of the thin slab casting shroud of the prior art 1 (the data indicated by the solid line) on the horizontal section of the crystallizer at the outlet of the shroud, and the upward swirling velocity near the narrow side of the crystallizer at both sides of the curve is also reduced, and the velocity at both sides is also relatively uniform, thereby controlling the flow velocity on the liquid surface of the crystallizer and making the liquid surface more stable, so as to avoid the occurrence of the "slag entrapment" phenomenon in the crystallizer.

[0061] Figure 12 A comparison of the velocity of the molten metal on the horizontal section at the outlet of the shroud for the application of the prior art 2 and the shroud of the present application when casting a medium-small section billet at a low casting speed in MCCR continuous casting.

[0062] As shown in the figure, the velocity distribution of the molten metal in the width direction of the crystallizer at the outlet of the shroud of the present application (the data indicated by the dotted line) is relatively more uniform and dispersed, and the maximum velocity thereof is increased by about 20% than the maximum velocity of the thin slab casting shroud of the prior art 2 (the data indicated by the solid line) on the horizontal section of the crystallizer at the outlet of the shroud, and the upward swirling velocity near the narrow side of the crystallizer at both sides of the curve is also increased, which is beneficial to bring the high-temperature molten metal to the liquid surface of the crystallizer, which is important for promoting the melting of the protective slag and the function of the metallurgical function, and at the same time, ensures that the "slabbing" phenomenon on the liquid surface of the crystallizer can be avoided under the stable state of the liquid surface of the crystallizer.

[0063] Therefore, the thin slab casting shroud of the present application is superior to the thin slab casting shroud of the prior art 1 and 2 in the velocity and temperature distribution of the molten metal in the crystallizer.

[0064] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacement or change or combination according to the technical solution and concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A submerged entry nozzle for thin slab continuous casting, comprising a nozzle body, a distributor, and a guide. The nozzle body has a molten metal channel extending along a central vertical axis, with a symmetrical cross-section. The molten metal channel has one inlet and at least one outlet. The nozzle body is composed of an inflow section, an expansion section, and an outflow section connected sequentially from top to bottom, with smooth transitions between the molten metal channels within each section. The nozzle body is characterized by: The outlet section of the aforementioned nozzle body is provided with a central flow divider, a pair of axially symmetrical outer flow dividers, and a pair of axially symmetrical guides; wherein: The central flow divider is located on the bottom central axis within the outflow section of the main body of the nozzle. The central flow divider has an upper top surface and a lower bottom surface, a pair of axially symmetrical side surfaces, and a central outflow channel. The upper top surface and the lower bottom surface of the central flow divider are both horizontal planes, and a pair of axially symmetrical grooves are provided on the two side surfaces of the central flow divider. The pair of axially symmetrical outer flow dividers are located between the central flow divider body and the corresponding sidewalls of the two water inlets. The outer flow dividers have a guide arc top surface, an inner guide inclined plane, an outer guide inclined plane, and a lower inclined bottom surface. The inner guide inclined plane of the outer flow dividers, together with the side surface of the central flow divider on the same side and the wide surface of the channel in the outflow section, constitute the main outflow channel of the water inlet. The outer guide inclined plane of the outer flow dividers, together with the side arc surface of the molten metal channel located near its outlet in the expansion section on the same side and the wide surface of the channel in the outflow section, constitute the two auxiliary outflow channels on the outer side of the water inlet. The pair of axially symmetrical guides are arranged on the upper part of the outlet section of the nozzle body. The guides have a top surface, a bottom surface, an outer inclined plane and an inner inclined plane. The top surface and the bottom surface of the guides are horizontal planes.

2. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The central distributor has a pair of axially symmetrical grooves on both sides, with the bottom depth decreasing from top to bottom. The upper part of the groove bottom is an arc surface that transitions to a middle and lower guide slope. The guide angle (γ) of the middle and lower guide slope of the central distributor groove is from 5 degrees and inclusive to 8 degrees and inclusive. The width of the groove on the side of the central distributor is 1 / 3 to 3 / 4 of the maximum width of the cross-section of the molten metal channel in the outflow section of the nozzle body.

3. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The width (b) of the bottom surface of the central distributor is 70 mm and includes 70 mm to 80 mm and includes 80 mm; the maximum width (a) of the top surface of the central distributor is 100% to 150% of the width (b) of the bottom surface of the central distributor and includes 100% to 150% and includes 150%; the height (h1) of the central distributor is greater than 1 / 2 of the distance (h2) between the bottom surface of the guide fluid and the bottom end face of the nozzle body, and less than 2 / 5 of the length (H3) of the outflow section of the nozzle body.

4. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The guiding angle (α) of the outer guiding inclined plane of the pair of axially symmetrical outer flow dividers is from 25 degrees and inclusive to 35 degrees and inclusive; the guiding angle (β) of the inner guiding inclined plane of the outer flow dividers is from 12 degrees and inclusive to 18 degrees and inclusive; the radius of curvature (r) of the top surface of the guiding arc of the outer flow dividers is 13 mm, from 10 mm to 15 mm; the lower inclined bottom surface of the outer flow dividers constitutes part of the bottom outer inclined end face of the outlet section of the nozzle body, and the horizontal inclination angle (θ) of the bottom outer inclined end face is from 40 degrees and inclusive to 50 degrees and inclusive.

5. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The minimum spacing (d) between the pair of axially symmetrical outer fluid distributors is 70% to 80% of the maximum length of the cross-section of the molten metal channel in the outflow section of the nozzle body; the distance (h3) from the highest point of the guide arc top surface of the outer fluid distributor to the bottom end face of the nozzle body is 80% to 90% of the length of the outflow section of the nozzle body.

6. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The minimum spacing (e) of the pair of axially symmetrical guides is 25% to 30% of the maximum length of the cross-section of the molten metal channel in the outflow section of the nozzle body, and is less than 50% of the minimum spacing (d) of the pair of axially symmetrical outer guides; the length of the outer inclined surface of the guide is greater than or equal to the length of its bottom surface, and less than 150% of the length of its bottom surface.

7. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The height of the top surface of the guide fluid is 0-10 mm lower than the upper edge of the auxiliary outflow channel hole, i.e., the inlet position of the outflow section of the nozzle body, and higher than the highest point of the arc top surface of the outer distributor fluid; the distance (h2) between the bottom surface of the guide fluid and the bottom end face of the nozzle body is 65%-70% of the length (H3) of the outflow section of the nozzle body, and lower than the highest point of the arc top surface of the guide fluid of the outer distributor fluid.

8. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The inclination angles of the inner and outer inclined planes of the fluid guide are the same as the inclination angle (β) of the inner guiding inclined plane of the outer fluid guide on the same side.

9. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The cross-sectional area at the outlet of the molten metal channel within the expansion section is 255% to 265% of the cross-sectional area at its inlet; the length (H2) of the expansion section is 5 / 7 to 7 / 9 of the total length of the nozzle body.

10. The submerged entry nozzle for thin slab continuous casting according to claim 1, characterized in that: The length (B) of the bottom middle horizontal end face of the outlet section of the sprue body is 50-60% of the maximum length (a31) of the cross-section of the molten metal channel in the outlet section of the sprue body, and the length (H3) of the outlet section of the sprue body is 1 / 9 to 1 / 8 of the total length of the sprue body.

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