Crystallizer for controlling sideline of medium-thickness plate and inhibiting angular crack defect

Abstract

The invention belongs to the technical field of steel continuous casting, and particularly discloses a crystallizer for controlling sidelines of a medium-thickness plate and inhibiting angular crack defects, which comprises an outer frame, two wide-surface copper plates and a narrow-surface copper plate are fixedly connected onto the outer frame, a plurality of cooling copper pipes are arranged on the back surface of the narrow-surface copper plate, a support plate is arranged below the narrow-surface copper plate, and foot rollers are rotatably connected onto the support plate. The foot roller is located below the narrow-face copper plate, the edge of the working face of the narrow-face copper plate is a flat face, the middle of the working face is an arc-shaped protruding face, the convexity value is 6 mm, and the width of the flat face from an upper opening to a lower opening of the narrow-face copper plate is linearly reduced. In order to solve the problem that linear defects appear on the edge in the current plate rolling process, the method controls the contour shape of a casting blank in the blank casting stage by designing a crystallizer with a convexity narrow-face copper plate so as to restrain the generation of the edge defects of steel, so that the linear defects and corner crack defects on the edge of a medium-thickness plate are overcome, and the production efficiency is improved. The surface quality of the plate is seriously influenced, so that the mechanical property of the plate is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of continuous casting of steel materials, and particularly relates to a mold for controlling edge lines and inhibiting corner crack defects of a medium plate. BACKGROUND

[0002] The medium plate is an important structural material, and is a kind of steel material with a specific thickness range, and the thickness is generally between 4.5 mm and 25.0 mm, and more than 25.0 mm is called a heavy plate. The medium plate is widely used in the fields of shipbuilding, bridge engineering, construction engineering, pressure vessels, wind power equipment and the like, and can also be used to manufacture furnace shells, furnace plates, automobile static steel plates, automobile beam steel plates and welded components and the like. The quality of the medium plate is directly related to the safety and reliability of the terminal product, however, in the production process of the medium plate, edge line cracks and corner crack defects have always been the key problems restricting the improvement of product quality. The edge line defects and corner crack defects of the steel plate not only affect the surface appearance of the steel plate, but also reduce the mechanical properties and service life of the steel plate, and a large amount of resources need to be invested for subsequent processing, which seriously weakens the market competitiveness of the product; at present, how to effectively control the edge line cracks and corner crack defects of the steel plate has become a technical problem urgently to be solved in the steel industry.

[0003] The edge line defect is also called edge folding defect or edge black line defect, and is macroscopically manifested as one or several straight small cracks at a distance of 30 mm-80 mm from the edge of the steel plate. Such cracks are parallel to the rolling direction and are uniformly or continuously distributed along the length direction of the steel plate, and generally need to be observed clearly through pickling process, and the crack depth is generally 0.2 mm-0.5 mm, and in severe cases, can reach more than 1 mm. The corner crack defect is mostly present at the corner of the casting blank, and is extended to the edge of the steel plate after rolling, and such defects are easy to expand in the subsequent rolling process, resulting in continuous or discontinuous cracks at the edge of the steel plate, and even causing the risk of plate rupture.

[0004] Therefore, in order to solve the above problems, it is necessary to design a mold for controlling edge lines and inhibiting corner crack defects of a medium plate, by designing a convex arc surface mold, optimizing the narrow surface cooling water quantity and the foot roller arc parameters, so as to control the profile of the casting blank from the casting blank forming stage, so as to achieve the purpose of inhibiting the generation of edge line defects and the propagation of corner crack defects of the steel plate in the later rolling process. SUMMARY

[0005] The present application aims to provide a mold for controlling edge lines and inhibiting corner crack defects of a medium plate, so as to solve the problems of the occurrence of edge line defects and corner crack defects of the medium plate, which seriously affect the surface quality of the plate and reduce the mechanical properties of the plate, so that the plate edge needs to be cut during the subsequent processing, and finally the yield of the steel plate is greatly reduced.

[0006] In order to achieve the above-mentioned purpose, the basic scheme provided by the present application is: a crystallizer for controlling the edge line of a medium plate and inhibiting corner crack defects, comprising an outer frame, two wide-face copper plates and two narrow-face copper plates, the narrow-face copper plate is composed of a flat plate and an arc-shaped plate, the flat plate and the arc-shaped plate are fixedly connected, the wide-face copper plate and the narrow-face copper plate are adjacently arranged, the two wide-face copper plates are oppositely arranged, the two narrow-face copper plates are oppositely arranged, a plurality of bolt holes are arranged on the wide-face copper plate and the narrow-face copper plate, the outer frame is connected with the wide-face copper plate and the narrow-face copper plate through the bolt holes, a plurality of cooling copper pipes are arranged on the wide-face copper plate and the narrow-face copper plate, a support plate is fixedly connected below the wide-face copper plate, a foot roller is rotatably connected on the support plate, and the foot roller is located below the narrow-face copper plate.

[0007] The present application has the following advantages: (1) In the present application, the narrow-face copper plate of the crystallizer is designed as a structure of "flat side + arc-shaped convex surface in the middle", thereby adapting to the non-uniform shrinkage of the medium plate continuous casting billet during the solidification process, reducing the air gap and friction between the billet shell and the copper plate, and avoiding cracks in the edge and corner of the steel due to blocked shrinkage; meanwhile, the arc radius of the arc-shaped convex surface of the narrow-face copper plate gradually decreases, thereby making the crystallizer form a certain taper, providing space for the shrinkage of the solidified shell, reducing the friction between the medium plate continuous casting billet and the copper plate, and reducing the risk of crack generation; (2) The width of the flat surface of the lower part of the narrow-face copper plate linearly decreases by 1 mm, further increasing the taper of the edge, and the vertex height of the arc-shaped convex surface of the narrow-face copper plate below 800 mm linearly decreases by 0.5 mm, thereby providing additional shrinkage space for the central region of the medium plate continuous casting billet, strengthening the stress release of the outlet region of the crystallizer, and preventing edge line cracks from being generated due to extrusion when the billet shell is separated from the crystallizer; (3) The wide-face copper plate and the narrow-face copper plate are covered with a Ni-Co alloy plating layer, and the thickness of the plating layer of the narrow-face copper plate linearly increases from 0.3 mm at the upper opening to 2.5 mm at the lower opening, thereby balancing the heat flow at different heights of the crystallizer, reducing stress concentration, and also improving the wear resistance and corrosion resistance of the crystallizer.

[0008] In the second scheme, which is a preferred scheme of the basic scheme, the cross-sectional radius of the top end of the arc-shaped plate is 844.3 mm, the cross-sectional radius of the bottom end of the arc-shaped plate is 913.8 mm, the distance between the two sides of the top end of the arc-shaped plate and the edge of the flat plate is 25 mm, and the distance between the two sides of the bottom end of the arc-shaped plate and the edge of the flat plate is 24.9 mm; the radius of the arc-shaped convex surface is optimized according to the height of the narrow-face copper plate, so that the crystallizer has a certain taper, thereby matching the shrinkage degree of the medium plate continuous casting billet at different heights in the crystallizer, reducing the formation of air gaps, and enabling the billet shell of the medium plate continuous casting billet to grow uniformly, thereby effectively preventing the generation of cracks in the edge and corner regions.

[0009] Scheme three, which is the preferred of the basic scheme, the distance between the top of the arc-shaped plate and the edge of the flat plate gradually decreases by 0.1mm, and the distance between the 404mm of the arc-shaped plate and the edge of the flat plate is 24.9mm; the width of the copper plate above the 404mm of the upper opening gradually decreases, which provides additional shrinkage space for the edge region of the plate, and the width of the copper plate below the 404mm of the upper opening is 24.9mm, which remains constant, thereby providing consistent and continuous support and guidance for the formed shell, thereby ensuring the straightness of the edge of the plate, and the gradually decreasing distance between the top of the arc-shaped plate and the edge of the flat plate significantly increases the taper of the edge region of the lower section of the copper plate, thereby providing space for the shrinkage of the plate, and also preventing the occurrence of edge crack or corner tearing caused by the transition friction or extrusion of the shell and the copper plate or the foot roller near the outlet of the mold.

[0010] Scheme four, which is the preferred of the basic scheme, the radius difference between the 800mm of the arc-shaped plate and the bottom end is 0.5mm; by reducing the height of the vertex of the arc-shaped convex surface to change the radius of the curved surface, the late stage of the center of the plate in the mold and the tensile stress caused by the shrinkage when leaving the mold are relieved, thereby reducing the risk of cracks at the junction of the center region and the corner of the plate.

[0011] Scheme five, which is the preferred of the basic scheme, the wide copper plate and the narrow copper plate are provided with a Ni-Co plating layer, the thickness of the plating layer of the narrow copper plate gradually increases from the top to the bottom, the thickness of the plating layer at the top is 0.3mm, and the thickness of the plating layer at the bottom is 2.5mm; the plating layer of the narrow copper plate at the upper opening is thin, the thermal resistance is small, and the heat conduction is fast, which is beneficial to the rapid formation of a shell with sufficient thickness for the plate, the plating layer of the narrow copper plate at the lower opening is thick, the thermal resistance increases, and the heat conduction slows down, which helps to prevent the shell from being over-thickened and brittle due to supercooling at the lower part of the mold, thereby reducing the internal and external temperature difference of the shell, making the shell temperature more uniform and plastic, and reducing the risk of cracks of the plate; and the Ni-Co alloy plating layer has high hardness, which can improve the wear resistance of the surface of the narrow copper plate, thereby effectively resisting the wear caused by the molten steel, reducing the high-temperature corrosion of the copper plate by the molten steel, and prolonging the service life of the copper plate. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a perspective view of a mold for controlling the edge line and suppressing the corner crack defects of a plate according to the present application; Figure 2 is a top view of a mold for controlling the edge line and suppressing the corner crack defects of a plate according to the present application; Figure 3This is a three-dimensional schematic diagram of a crystallizer for controlling the edge line of a medium-thick plate and suppressing corner crack defects according to the present invention; Figure 4 This is a side view of a crystallizer for controlling the edge line of a medium-thick plate and suppressing corner crack defects according to the present invention; Figure 5 This is a schematic diagram showing the dimensions of the crystallizer at distances of 104mm, 204mm, 304mm, 504mm, 604mm, 704mm, and 804mm from the narrow copper plate in a crystallizer for controlling the edge line of a medium-thick plate and suppressing corner crack defects, according to the present invention. Detailed Implementation

[0013] The present invention will be further described in detail below through specific embodiments: The accompanying drawings in the instruction manual include: 1. Outer frame; 2. Wide copper plate; 3. Narrow copper plate; 4. Bolt holes; 5. Cooling copper pipes; 6. Support plate; 7. Foot roller.

[0014] Example A crystallizer for controlling the edge lines of medium-thick plates and suppressing corner crack defects, such as... Figures 1 to 5 The diagram shows an outer frame 1, two wide copper plates 2, and two narrow copper plates 3. Each narrow copper plate 3 consists of two parts: a flat plate and an arc-shaped plate, which are fixedly connected. The cross-sectional radius of the top of the arc-shaped plate is 844.3 mm, and the cross-sectional radius of the bottom of the arc-shaped plate is 913.8 mm. The distance from the top two sides of the arc-shaped plate to the edge of the flat plate is 25 mm, and the distance from the bottom two sides of the arc-shaped plate to the edge of the flat plate is 24.9 mm. The radius difference between the arc-shaped plate at 800 mm and the bottom is 0.5 mm. The distance from the top of the arc-shaped plate to the edge of the flat plate gradually decreases from the top to 404 mm, with a decrease value of 0.1 mm. The distance from the arc-shaped plate to the edge of the flat plate at 404 mm and below is 24.9 mm. m, wide copper plates 2 and narrow copper plates 3 are arranged adjacent to each other, two wide copper plates 2 are arranged opposite each other, and two narrow copper plates 3 are arranged opposite each other. Several bolt holes 4 are provided on the back of the two wide copper plates 2 and narrow copper plates 3. The outer frame 1 is bolted to the wide copper plates 2 and narrow copper plates 3 through the bolt holes 4. Both wide copper plates 2 and narrow copper plates 3 are provided with Ni-Co plating. The plating thickness of the narrow copper plate 3 gradually increases from the top to the bottom. The plating thickness at the top of the narrow copper plate 3 is 0.3mm and the plating thickness at the bottom is 2.5mm. Several cooling copper pipes 5 are provided through both wide copper plates 2 and narrow copper plates 3. A support plate 6 is provided directly below the narrow copper plate. A foot roller 7 is rotatably connected to the support plate 6. The foot roller 7 is located below the narrow copper plate 3.

[0015] The embodiment of the present application is that when casting is needed, the outer frame 1 is first fixed on the vibrator, then cooling water is injected into the cooling copper pipe 5 at a flow rate of 702 L / min, then the molten steel in the tundish is injected into the rectangular cavity formed by the wide copper plate 2 and the narrow copper plate 3, after the molten steel contacts the wide copper plate 2 and the narrow copper plate 3, the surface layer of the molten steel is rapidly solidified under the action of the cooling water to form a shell, then the formed steel billet is moved downward by rotating the foot roller 7, until the steel billet is completely removed from the lower opening of the crystallizer, and finally the steel billet is conveyed to the cooling section for secondary cooling.

[0016] The above-mentioned is only the embodiment of the present application, and the common knowledge of specific structures and characteristics in the scheme is not described in detail. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A crystallizer for controlling the edge lines of medium-thick plates and suppressing corner crack defects, characterized in that, The device includes an outer frame (1), two wide copper plates (2) and two narrow copper plates (3). The narrow copper plates (3) are composed of two parts, including a flat plate and an arc plate. The flat plate and the arc plate are fixedly connected. The wide copper plates (2) and the narrow copper plates (3) are arranged adjacent to each other. The two wide copper plates (2) are arranged opposite to each other. The two narrow copper plates (3) are arranged opposite to each other. Several bolt holes (4) are provided on the two wide copper plates (2) and the narrow copper plates (3). The outer frame (1) is bolted to the wide copper plates (2) and the narrow copper plates (3) through the bolt holes (4). Several cooling copper pipes (5) are provided through the two wide copper plates (2) and the narrow copper plates (3). A support plate (6) is fixedly connected directly below the wide copper plate (2). A foot roller (7) is rotatably connected to the support plate (6). The foot roller (7) is located below the narrow copper plate (3).

2. A crystallizer for controlling the edge line of medium-thick plates and suppressing corner crack defects according to claim 1, characterized in that, The cross-sectional radius of the top end of the arc-shaped plate is 844.3 mm, the cross-sectional radius of the bottom end of the arc-shaped plate is 913.8 mm, the distance from the top two sides of the arc-shaped plate to the edge of the flat plate is 25 mm, and the distance from the bottom two sides of the arc-shaped plate to the edge of the flat plate is 24.9 mm.

3. A crystallizer for controlling the edge line of medium-thick plates and suppressing corner crack defects according to claim 1, characterized in that, The distance from the top of the arc plate to the edge of the flat plate gradually decreases by 0.1mm on both sides from the top of the arc plate to 404mm, and the distance from the edge of the flat plate on both sides at and below 404mm is 24.9mm.

4. A crystallizer for controlling the edge line of medium-thick plates and suppressing corner crack defects according to claim 1, characterized in that, The radius difference between the 800mm mark and the bottom of the arc-shaped plate is 0.5mm.

5. A crystallizer for controlling the edge line of medium-thick plates and suppressing corner crack defects according to claim 1, characterized in that, Both the wide copper plate (2) and the narrow copper plate (3) are provided with Ni-Co plating. The plating thickness of the narrow copper plate (3) gradually increases from the top to the bottom. The plating thickness at the top of the narrow copper plate (3) is 0.3 mm and the plating thickness at the bottom is 2.5 mm.

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