Crystallizer cavity structure
阅读说明：本技术 一种结晶器腔形结构 (Crystallizer cavity structure ) 是由 刘强 韩志伟 邓比涛 孔意文 于 2020-07-08 设计创作，主要内容包括：本发明涉及一种结晶器腔形结构,属于金属连续铸造领域。该腔形结构由四块铜板合围成管,其中两块相向设置的铜板为宽面板,另两块相向设置的铜板为窄面板；宽面板为曲面板；沿结晶器浇铸方向,该曲面板的板面呈连续矫直曲线变化；沿结晶器水平方向,该曲面板的板面呈分段函数曲线变化。通过应用连续矫直曲线,使得结晶器在其入口处的曲率不为0,在结晶器的有限长度内,铸坯坯壳整体应变小且恒定,应变速率低,改善了铸坯质量；克服了传统薄板坯结晶器铸坯坯壳在结晶器内应变速率过大的问题,改善了铸坯表面的裂纹缺陷、减少了铸坯对结晶器铜板镀层的磨损,延长了结晶器的使用寿命。(The invention relates to a crystallizer cavity structure, and belongs to the field of metal continuous casting. The cavity-shaped structure is formed by encircling four copper plates into a tube, wherein two copper plates which are arranged oppositely are wide panels, and the other two copper plates which are arranged oppositely are narrow panels; the wide panel is a curved plate; along the casting direction of the crystallizer, the plate surface of the curved plate changes in a continuous straightening curve; along the horizontal direction of the crystallizer, the plate surface of the curved plate is changed in a piecewise function curve mode. By applying the continuous straightening curve, the curvature of the crystallizer at the inlet of the crystallizer is not 0, the integral strain of the casting blank shell is small and constant within the limited length of the crystallizer, the strain rate is low, and the quality of the casting blank is improved; the problem that the strain rate of a casting blank shell of the traditional sheet billet crystallizer in the crystallizer is too high is solved, the defect of cracks on the surface of the casting blank is overcome, the abrasion of the casting blank on a crystallizer copper plate coating is reduced, and the service life of the crystallizer is prolonged.)
1. A crystallizer cavity-shaped structure is characterized in that four copper plates surround a pipe, wherein two copper plates arranged in opposite directions are wide panels, the other two copper plates arranged in opposite directions are narrow panels, and the width of each wide panel is larger than that of each narrow panel; the method is characterized in that: the wide panel is a curved plate; along the casting direction of the crystallizer, the plate surface of the curved plate changes in a continuous straightening curve; along the horizontal direction of the crystallizer, the plate surface of the curved plate is changed in a piecewise function curve mode.
2. The crystallizer cavity structure of claim 1, wherein: the continuous straightening curve is:
wherein: y ismaxHalf the maximum thickness in mm of the horizontal section of the crystallizer at the z-height position of the crystallizer;
lm-crystallizer length, in mm;
z-coordinate value in the casting direction z, unit mm;
unit mm;
Wb-thickness of the lower mouth of the crystallizer in mm;
Δ C-shrinkage per unit length;
Δ W is half of the maximum width of the upper opening of the crystallizer and the unit is mm.
3. The crystallizer cavity structure of claim 1, wherein: the wide panel is symmetrical left and right along the center of the panel surface.
4. The crystallizer cavity structure of claim 3, wherein: the center of the board surface of the wide board is taken as a boundary, and the piecewise function curve at one side of the wide board is as follows:
wherein: y is half of the thickness of the wide panel corresponding to a certain coordinate position in the z height position and the x direction of the crystallizer and the unit mm;
unit mm;
x is a coordinate value in the x direction in the horizontal direction and the unit is mm;
C1、C2、C3are the boundary points of the piecewise function.
Technical Field
The invention belongs to the field of metal continuous casting, and particularly relates to a crystallizer cavity structure.
Background
The continuous casting and rolling process of the sheet billet has the advantages of simplified process, short production flow, less equipment, energy conservation, high yield and the like, can more flexibly face the market, and becomes an important investment object of steel production companies in recent years. The most important difference between the continuous thin slab casting and rolling technique and the conventional continuous casting technique is the crystallizer. As is well known, in order to solve the problems of molten steel flowing in the gap between the mold and the nozzle, the mold is designed into a funnel shape with a large top and a small bottom, but the design makes the shell of the billet subjected to additional stress in the mold to easily cause crack defects, so the shape curve of the inner cavity of the mold is of great importance, and as a core technology of continuous casting of thin slabs, the design of the shape curve of the inner cavity of the mold has been paid great attention by those skilled in the art.
In the prior art of thin slab funnel-shaped crystallizers, the transverse and longitudinal curves thereof comprise: the curve is formed by connecting a plurality of sections of straight lines, connecting the straight lines with circular arcs, and forming a double arc and an ellipse or combining polynomial curves. The boundary conditions of the constraint curve include: the curve end point value, the curve first derivative is continuous, the curve second derivative is continuous, the curve third derivative is continuous, the curve curvature is constant, the curve curvature change rate is minimum, the curve curvature change rate is constant and the like, so that the final curve equation is solved.
A Chinese patent application with the application number of 201910263801.X, namely a thin slab funnel-shaped crystallizer wide-surface copper plate based on a relaxation curve and a preparation method thereof, discloses a funnel-shaped crystallizer cavity curve based on a relaxation curve, wherein the curve is expressed as a curve in the horizontal direction of a crystallizer
The Chinese patent application No. 200410015897.1 entitled "Water-cooled crystallizer for continuous Metal casting" discloses a cavity curve of a funnel-shaped crystallizer, which is arranged in the horizontal direction of the crystallizerThe curve part equation of the cross-sectional profile curve is expressed as f (x) a0+a1x+a2x2+a3x3+a4x4+a5x5+a6x6In the casting direction of the mold, the equation for the curve portion of the longitudinal section profile curve is expressed as f (z) ═ b0+b1z+b2z2+b3z3+b4z4+b5z5The boundary condition of the constraint curve is that the reciprocal of the curve is continuous above the third order, and the like.
In the article "obtaining the curved surface of the wide surface part of the inner cavity of the crystallizer for continuous casting of an ideal thin slab", it is disclosed that the crystallizer adopts a curve in the casting direction ofThe boundary conditions for the constraint curve are that the first and second derivatives of the curve at the end points are both zero and that the maximum value of the rate of change of curvature is minimal.
However, the above curves have disadvantages that the curvature of the curve in the longitudinal direction, or at the inlet and outlet of the mold is 0, or the longitudinal curve passes through a circular arc transition in a short interval, or the constant strain rate of the cast slab in the longitudinal direction cannot be ensured, so that the limited length of the cast slab in the mold is generally not more than 1200mm, the strain rate is increased, and the stress strain of the continuous casting shell in the mold is increased.
Disclosure of Invention
In view of the above, the present invention provides a mold cavity structure based on a continuous straightening curve to overcome the problem of an excessive strain rate of a thin slab shell in a mold.
In order to achieve the purpose, the invention provides the following technical scheme:
a crystallizer cavity-shaped structure is characterized in that four copper plates surround a pipe, wherein two copper plates arranged in opposite directions are wide panels, the other two copper plates arranged in opposite directions are narrow panels, and the width of each wide panel is larger than that of each narrow panel; the wide panel is a curved plate; along the casting direction of the crystallizer, the plate surface of the curved plate changes in a continuous straightening curve; along the horizontal direction of the crystallizer, the plate surface of the curved plate is changed in a piecewise function curve mode.
Further, the continuous straightening curve is:
wherein: y ismaxHalf the maximum thickness in mm of the horizontal section of the crystallizer at the z-height position of the crystallizer;
lm-crystallizer length, in mm;
z-coordinate value in the casting direction z, unit mm;
unit mm;
Wb-thickness of the lower mouth of the crystallizer in mm;
Δ C-shrinkage per unit length;
Δ W is half of the maximum width of the upper opening of the crystallizer and the unit is mm.
Further, the wide panel is symmetrical left and right along the center of the panel.
Further, the center of the board surface of the wide board is taken as a boundary, and the piecewise function curve at one side of the wide board is as follows:
wherein: y is half of the thickness of the wide panel corresponding to a certain coordinate position in the z height position and the x direction of the crystallizer and the unit mm;
unit mm;
x is a coordinate value in the x direction in the horizontal direction and the unit is mm;
C1、C2、C3are the boundary points of the piecewise function.
The invention has the beneficial effects that:
according to the invention, by applying the continuous straightening curve, the curvature of the crystallizer at the inlet of the crystallizer is not 0, the whole strain of the casting blank shell is small and constant within the limited length of the crystallizer, the strain rate is low, and the quality of the casting blank is improved; the problem that the strain rate of a casting blank shell of the traditional sheet billet crystallizer in the crystallizer is too high is solved, the defect of cracks on the surface of the casting blank is overcome, the abrasion of the casting blank on a crystallizer copper plate coating is reduced, and the service life of the crystallizer is prolonged. And in the direction perpendicular to the pouring direction, the casting blank stress concentration caused by the curved surface form can be relieved by adopting the piecewise function, and the function of reducing crack defects is played to a certain extent.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a three-dimensional view of the crystallizer cavity structure;
FIG. 2 is a top view of the crystallizer cavity structure;
FIG. 3 is a right side view of the crystallizer cavity structure;
FIG. 4 is a schematic view of a straightening curve;
FIG. 5 is a graph showing the variation of the central thickness of the crystallizer along the casting direction;
fig. 6 is a variation of the curvature of the thickness variation curve along the casting direction.
Reference numerals:
wide panel I-1, wide panel II-2, narrow panel I-3, narrow panel II-4, wide panelwidth-W1Narrow panel width-W2。
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Referring to fig. 1 to 3, a mold cavity structure is shown, the mold cavity structure is formed by four copper plates enclosing a tube, wherein two copper plates disposed opposite to each other are wide plates, which are correspondingly referred to as wide platesI1, a wide panel II 2, and the other two copper plates which are oppositely arranged are narrow panels which are correspondingly marked as a narrow panel I3 and a narrow panel II 4; width W of wide panel I1 and wide panel II 21Greater than the width W of the narrow panel2(ii) a The wide panel I1 and the wide panel II 2 are curved plates; along the casting direction of the crystallizer, the plate surface of the curved plate changes in a continuous straightening curve; along the horizontal direction of the crystallizer, the plate surface of the curved plate is changed in a piecewise function curve mode.
By applying the continuous straightening curve, the curvature of the crystallizer at the inlet of the crystallizer is not 0, the integral strain of the casting blank shell is small and constant within the limited length of the crystallizer, the strain rate is low, and the quality of the casting blank is improved; the problem that the strain rate of a casting blank shell of the traditional sheet billet crystallizer in the crystallizer is too high is solved, the defect of cracks on the surface of the casting blank is overcome, the abrasion of the casting blank on a crystallizer copper plate coating is reduced, and the service life of the crystallizer is prolonged. And in the direction perpendicular to the pouring direction, the casting blank stress concentration caused by the curved surface form can be relieved by adopting the piecewise function, and the function of reducing crack defects is played to a certain extent.
FIG. 4 is a schematic view of a straightening curve with radius R0The arc section AB is transited to a straight line section CD through a continuous straightening curve of the BC section, and the general form of the BC section isIn the formula, y is the y-axis coordinate of the straightening curve and is in mm; x is the x-axis coordinate of the straightening curve and is in mm; s is the arc length of the straightening curve in mm; replacing the projection length L of the arc length s on the x axis with the projection length L of the arc length s for simplified calculation, and obtaining the arc length
And establishing a space rectangular coordinate system by taking the center of the inlet of the crystallizer as an origin, wherein the z axis is the casting direction, and the plane where the x axis and the y axis are located is a horizontal plane vertical to the casting direction. As shown in fig. 1, AA' is a curve that is a continuous straightening curve change along the casting direction according to the present embodiment, and can be obtained by coordinate transformation:
wherein: y istIs the y-axis coordinate of the point A in unit mm;
ytis the y-axis coordinate of the point A' in mm;
lmis the length of the crystallizer in mm;
z is the coordinate value of the z axis (casting direction) in mm;
a 'O' is half the thickness of the crystallizer outlet (lower mouth) in mm, a parameter generally known and used
AO is half of the thickness of the crystallizer inlet (upper opening) in mm, the parameter is related to the natural shrinkage of the steel during cooling, the shrinkage coefficient is generally a fixed value deltaC, and the shrinkage is gradually increased from A to A', generally expressed as
R is the radius of the starting point of the continuous straightening curve, namely the curvature radius of the curve AA' at the point A, and the unit is mm;
from this, the continuous straightening curve can be expressed as:
y in the formulamaxIs half of the maximum thickness of the crystallizer at different height positions, namely half of the maximum thickness of the horizontal section of the crystallizer at the z-height position of the crystallizer, and the unit is mm.
When z is equal to 0, the ratio of z,
Preferably, the wide panel is left-right symmetrical along the center of the panel surface. Referring to fig. 1 and 2, the wide panel i 1 and the wide panel ii 2 are symmetrical to each other about the plane yoz.
The curve of the wide panel I1 on the right side of the plane of the yoz is changed in a piecewise function manner in the direction vertical to the casting direction by taking the center of the panel surface of the wide panel as a boundary, namely the plane of the yoz.
As shown in fig. 2, the piecewise function is divided into 4 intervals, AB, BC, CD, DE, and the y values of the different intervals are represented by different functions.
For the OB' interval: y ═ ymax，——(0)。
For the B 'C interval, any y ═ PP', Δ B 'KO "is similar to Δ PP' K according to the triangle-like theorem, then:
wherein: KP ' ═ x-OB ' -B ' K, — (2);
B′O″＝BO″-BB′＝r-ymax，——(3)；
the combined vertical type (4) and the formula (5) can obtain
The joint type (1), (2), (3) and the formula (6) can obtain:
for the C 'D' interval: any y ═ QQ '═ O' D '-O' D ═ r-rcos β, - (8);
and is
Simultaneous reaction of (8) and (9) gives
For the D 'E' interval: y is the sum of half of the thickness of the crystallizer outlet (lower opening) and the natural shrinkage, namely
By combining (0), (7), (10) and (11), the piecewise function y can be expressed by the following relation:
wherein: y is a function of x and z, which is half of the thickness of the wide panel corresponding to a certain coordinate position in the z height position and the x direction of the crystallizer and is unit mm;
r is a variable, and according to the triangle similarity principle, Δ O ' D ' N is similar to Δ O "B ' N, so that:
namely, it is
sinγ2+cosγ2＝1，——(15)；
Vertical combined type (12) to type (15)The following can be obtained:unit mm;
the delta E is the variable in the variable,unit mm;
x is a coordinate value in the x direction and is in unit mm;
C1is the boundary point of the piecewise function, i.e., point B' in fig. 2; c1May be 0, i.e., it means that the straight line segment may not be present;
C2is the boundary point of the piecewise function, i.e., point C' in fig. 2;
C3is the boundary point of the piecewise function, i.e., point D' in FIG. 2; x is not less than C3The straight line segments of (a) may be absent.
The following is a proof of description by way of specific examples:
a crystallizer for the thin slab of steel mill is composed of four copper plates, two wide and two narrow copper plates, and features that the wide copper plate is curved, the outlet of said crystallizer is 100mm × 1300mm, and the length of said crystallizer is lm1200mm, 181.8mm in the maximum width of the upper mouth, 0.003 in the shrinkage Δ C per unit length, and 0.003 in the thickness W of the lower mouthb＝100mm。
Then
Then
The wide panel is symmetrical left and right along the center of the panel. The center of the plate surface of the wide plate is used as a boundary, and the right side of the wide plate changes in a piecewise function manner along the direction vertical to the pouring direction: wherein C is1＝AB＝90mm；C2＝AC＝270mm，C3＝AD＝450mm；
Then
Then
Then
The curved surface of the copper plate of the crystallizer is obtained by calculation, the change curve of the thickness of the center of the crystallizer along the casting direction is shown in figure 5, the change condition of the curvature is shown in figure 6, and as can be seen from figure 6, the curvature is 0.00016 at the upper opening of the crystallizer, the strain and the strain rate of a casting blank shell in the crystallizer can be greatly reduced, and the strain of the casting blank in the crystallizer is constant; the curvature of the lower opening is 0 and is tangent to the guide section at the back; the quality of the casting blank is improved.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
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