CN1123528A - Improved mould for steel continuous casting, particularly for the continuous casting of thin slabs - Google Patents

Abstract

An improved mould, particularly suitable for the continuous casting of thin slabs, shows the wide walls having a profile in a vertical plane being formed of a number of curved lines which are radiused to each other, in particular arcs of circumference having a bending radius of a size decreasing downward from a value approaching infinity on the inlet side where the tangent line to the profile is vertical, until reaching with a continuous line the known lower band at the outlet from the mould. The latter is an arc of circumference with the center in the oscillating center of mould, being positioned at a height comprised between the levels of inlet and outlet sides of the mould itself. Preferably the profile pattern is elliptical starting from the inlet side with vertical tangent down to said lower arc of circumference, so that the bending variation is caused to be tendentially continuous.

Description

The modified mould that is used for the continuous casting of the continuous casting of steel, particularly slab ingot

The present invention relates to be used for the continuous casting of steel, particularly be applicable to that continuous casting thickness is preferably less than the modified mould of 70mm slab ingot.

As everybody knows, even when cast thickness 〉=240mm and common steel ingot, generally allow the inhomogeneities that being formed with of epidermis is certain, but when the above-mentioned slab ingot of casting, (the highest casting speed of common steel ingot is 1.5m/min because main casting speed when these slab ingots are directly delivered to rolling workshop section is very high, and the casting speed of slab ingot is 3-6m/min), a series of problems will take place, inhomogeneous cooling causes product quality to descend, owing to the temperature difference forms versicolor vertical rule, thereby make slab ingot thickness irregular, be epidermis possibility " cracking " when solidifying mainly, thereby jeopardize whole casting machine inevitably in another the most serious problem that occurs under the higher casting speed.

DE-A-4031691 discloses a kind of mould of casting slab ingot, it has two relative inner panel and outside plates with middle concave surface, the first length approximate vertical of these plates, it rise from the entrance region of this mould, end at half place of plate hight, then the curved shape of the decline of mould outlet, the bending radius of the bending radius of inner panel (soffit plate) and outside plate (hogback plate) is basic identical, also can be less than the thickness of a slab ingot.

Though its inner and outer plates has undeniable advantage by the mould of the described feature manufacturing of DE-A-4031691 than existing mold, especially with regard to having better cooling uniformity, and this foundry goods is directly delivered to rolling workshop section without middle process be extremely important, but do not solve foundry goods may break away from mold wall in the unexpected change of camber zone problem.This can cause vertical discontinuity, thereby not only causes inhomogeneous cooling even, and can cause local mechanical stress (causing compression and tensile stress respectively on soffit plate and hogback plate), thereby may the crack take place and finally cause molten steel to flow out in the maximum district of stress.

Therefore the present invention is intended to by the shape of improving mould inner and outer plates itself mould be worked better, make foundry goods press close to mold wall as far as possible, thereby make the heat radiation of foundry goods maximum and even as far as possible, and the change of camber is continuous as far as possible up to final curved portions from the import department with vertical tangent line downwards.Therefore the longitudinal profile linear portions of the basic surface of the soffit plate of mould and hogback plate has been done improvement.

These purpose apparatus requirement 1 described feature of having the right, mould is realized.

Should see, can be used in the mould of having mentioned among DE-A-4031691 above of concave surface in upper area has by the described mould vertical profile line style that in a vertical plane, forms of claim 1 essential characteristic or by the described oval vertical profile line style of claim 2 by some curves that are mutually fillet, but also can be used on do not have this in concave surface, its broad both sides or relatively inner and outer plates (soffit plate and hogback plate) in the mould of upper inlet edge almost parallel.

From below in conjunction with accompanying drawing to can clearlyer finding out the above-mentioned of mould of the present invention and other purpose, advantage and feature the detailed description of the present invention's one non-limitative preferred embodiment.In the accompanying drawing:

Fig. 1 is the longitudinal sectional drawing of two plates on this mould of formation broad both sides;

Fig. 2 and Fig. 3 example respectively illustrate the radius of curvature R-R of buttocks of the basic surface of hogback plate and soffit plate ₄Change conditions; And

It is that the circumference bending radius tangent, that order at B of R is the ellipse of R at this point and a radius that Fig. 4 letter illustrates by 1 B, and Fig. 4 a is the enlarged detail of Fig. 4, so that see clearlyer.

Referring to Fig. 1, mould for continuous casting of the present invention is made of copper coin that is respectively hogback plate and soffit plate 1 and the 1a as its broad both sides, also be that the relative vertical line of this two plate is crooked slightly, thereby lead to a below curved path (not shown) that is specially adapted to produce the continuous casting installation for casting of slab ingot continuously.

As previously mentioned, only at lower area, promptly making an appointment with half highly to form this camber, the remainder approximate vertical in the existing plate.

Two relative plate 1,1a are cooled off by the fluid media (medium) among any known type water tank 2, the 2a.As mentioned above, the upper area of mould can have concave surface in, thereby only the place, end on the less both sides of mould is parallel to each other in the cross section for two plates.In fact, two plates at a distance of a bigger distance, so that reserve more spaces for the nozzle of submergence, thereby guarantee that molten steel has enough wide thermally-stabilised surface between plate and nozzle at the middle part, thereby help the fusing of powder on the face and obtain the best and lubricate.In any case, hereinafter the feature that will illustrate only focus on two plates buttocks bending and with do not have not in concave surface irrelevant, thereby described buttocks or the real buttocks of the inner surface of plate in no matter which vertical section, or desirable, so-called " substantially " surperficial buttocks, upper face central region leave this surface and form above-mentioned in concave surface.Still with regard to described " basic surface ", it can be the above-mentioned ideal surfaced in the mould of middle concave surface of tool, or the real inner surface of two plates.

Be the geometric properties of the basic surface of clearer expression hogback plate and soffit plate, can express the inner surface of Die and mould plate one embodiment shown in Figure 1 and the example that a vertical plane intersects the buttocks that forms among the figure referring to Fig. 2 and Fig. 3.In this two figure, 0 expression mould be positioned at this buttocks centre of oscillation on half horizontal line of highly locating approximately, this centre of oscillation overlaps with the flexural center of this buttocks at the last part at mould outlet place.According to prior art, this last part that the flexural center of this buttocks overlaps with the mould centre of oscillation along half stretching, extension of pact of the height of plate and constitute this basic surface buttocks the curve district only arranged, and all the other are straight line substantially.

According to the present invention, basic surface this buttocks in vertical plane all is a curve, it is made of the some sweeps with different radii that are mutually continuous fillet, in other words, there is common tangent line at tie point place between the adjacent curve and does not form the turning, last part up to this mould outlet place, this last part is made of one section circular arc that its center of circle overlaps with the mould oscillation point, thereby this circular arc of two plates has predetermined radii, for example 5000 and 5500mm between (radius of this circular arc of outside plate or hogback plate is 5200mm in Fig. 2), and this radius of inner panel (soffit plate) is with respect to the radius of the hogback plate thickness less than slab ingot.

According to first embodiment of the invention, this buttocks is divided into some circular arcs (being 5 sections circular arcs) with identical central angle alpha in Fig. 2 and Fig. 3, and the end points that the center of circle of each circular arc is positioned at by the adjacent circular arc in top also is on the RADIAL of below circular arc starting point.In fact, some O ^IVBe positioned on the die inlet horizontal edge line apart from its opening one segment distance R ₄The place.First arc section between top point F, the E is therefore with R ₄For turning over an angle [alpha] downwards, arc radius arrives the E point, and the center of circle O of second circular arc E-D ^IIIPromptly at an E and center of circle O ^IVLine on, and so on.Just overlap with the tangent line of circular arc E-D at the tangent line of the circular arc E-F of E place like this, this curve just is circular arc and do not produce the turning fully.This point be equally applicable between the adjacent in twos circular arc have a few, the some B between circular arc C-B and last circular arc A-B, the center of circle of circular arc A-B is the centre of oscillation of mould just.

In fact, in order to make this buttocks according to the inventive method structure, the circular arc A-B that can its geometric properties has obtained to stipulate is as starting point, then by with the extended line of straight line O-B of the contact point B of adjacency circular arc B-C on determine the center of circle O of circular arc B-C ^I, and so on.Circular arc B-C and thereafter can be optional by simple geometric and triangulation calculation up to the length of each circular arc of a F preferably adopts and calculates easy fixed condition really, for example when determining the circular arc number of partitions of length B-F or consider a some O ' ... O ^IVAt the subpoint S ' that passes through on the horizontal line of O ... S ^IVThe central angle that Shi Caiyong is same.Divide equally each circular arc and each central angle and can be convenient to calculate and simplify the design of plate, but In the view of the present invention be not be far from it do can not, but the length of circular arc and corresponding central angle can increase continuously.

According to illustrated embodiment, center of circle O is positioned on half height of pact of mould, and more definite theory is positioned at the middle part of the length of camber change, and this length ends at a circular arc at the top, and this circular arc is vertical at the tangent line at the F place, summit that overlaps with the nearly oral region of mould, and its center of circle O ^IVBe positioned on the horizontal line by same point F.Should see that the buttocks of the basic surface of two plates can be divided into the quantity arc section different with illustrated embodiment,, thereby obtain the better curve of continuity more preferably greater than 5.Obviously, infinitely great if the Circular Arc that this buttocks is divided into is tending towards, then this curve becomes the camber curve that singly shakes of change continuously.During the mould vibration, the lower area that has than heavy camber of two plates is buttocks and the vibration little zone of difference, path, and this difference is on mould top or the entrance region maximum, but because basic radius R is very big, therefore almost is not aware of by laterally moving that vibration causes.Therefore, even in this zone, do not form concave surface in the inner surface centre of hogback and soffit plate, the inwall of two plates does not have the danger of the nozzle of running into submergence yet during vibration.

According to one embodiment of the present invention, the position of the inner surface of two templates in the space varies to the formed continuous change curve of bottom place's circular arc for oval continuously from the vertical tangential direction on summit.Oval circular arc between Fig. 2,3 some F and some B the condition that must satisfy have: the tangent line on the top is vertical; The tangent line of bottom with overlap with the tangent line of the final circular arc of this ellipse adjacency at Fig. 2,3 some B place; Equal the radius R of this circular arc at this locational bending radius ρ.

Fig. 4 and among the enlarged drawing 4a of meaningful part, it is oval to show an example, its four-quadrant can be determined this ellipse circular arc between needed Fig. 2,3 some F and the some B, for structure is made this ellipse, need only remember above-mentioned condition and use few simple geometry rule to get final product.

From crossing vertically this requirement of tangent line of some F, can derive oval center of circle O ¹Should be on horizontal line by a F.The Cartesian coordinates that so just can draw, its initial point is O ', transverse axis X is that O ' F overlaps with oval minor axis b.Therefore first batch of unknown quantity to be determined being arranged is the length of minor axis b and the major axis of the vertical O of passing through ' that overlaps with longitudinal axis y.If O is that the centre of oscillation of mould is being that the x of initial point, the coordinate in the y axle system are respectively m and n with O ', then the coordinate as some B on the ellipse is respectively: X _B=bcost; y _B=asint, wherein t is axle x and the angle of line of some O ' with some H, and H is for being the circumference of radius with a and horizontal intersection point by B, this line also passes through the some K on the vertical line of some B.If as being the center of circle with O, is B m 1 point on the circle of radius with R, then in this coordinate system, can establish an equation down: X=Rcos ξ+m; y _B=Rsin ξ+n, wherein, angle ξ was the angle between the horizontal line of O and the line of putting O and B.These two groups of coordinate figures are equated, calculation level B place is as the camber radius ρ of the function of these coordinates, and this ρ must equal known radius R (promptly apart from OB), is not simply but with the calculating that triangle can achieve a solution, can establishes an equation down by a series of: $\left(I\right)a=\frac{R\sin \mathrm{\ξ}+n}{\sin t}$ $\left(\mathrm{II}\right)\mathrm{ab}=\frac{\mathrm{tg\ξ}(R\sin \mathrm{\ξ}+n{)}^2}{\mathrm{tgt}\·{\sin }^{2}t}$ $\left(\mathrm{III}\right){\cos }^{4}t=\frac{R^2}{\mathrm{tg\ξ}(\mathrm{Rsn\ξ}+{n)}^2(\mathrm{tg\ξ}+1{)}^3}$

Although the ordinate n of some O is in front as unknown number, it is positioned at the bottom with respect to the mould upper end as the centre of oscillation, so the ordinate n that O is ordered can determine arbitrarily.Therefore, this ordinate n is zero between (do not have ellipse this moment and only have one section circular arc AF) and the yB (this moment B Ξ F must be arranged, because the tangent line that circular arc is ordered at B should be vertical, thereby the arc of ellipse reduces into this point).The value of n in Fig. 2 (on the hogback plate) is 400mm.By for example the inclination angle of the tangent line that B is ordered (equal 90 °+ξ) determine angle ξ after, and consider R yes known quantity (in Fig. 2, concerning the hogback plate, being 5200mm), can be from the equation III value of obtaining t.I can obtain a this value substitution equation, can obtain b immediately from equation II again.Like this, oval major and minor axis is definite, must determine that the position of O on axle x, its center of circle can determine this ellipse, and this need only obtain m, i.e. the abscissa of O ', and m can obtain from following formula: m=bcost-Rcos ξ.

In fact, for determining the buttocks of inside and outside two plates, need only calculate the coordinate x of the series of points M on the desirable ellipse in the middle of two buttocks of soffit plate and hogback plate _MAnd y _M, the number of point can be many arbitrarily.If represent that with Δ (for example Δ=30mm), then the coordinate of last 1 P of soffit plate (inner panel) is: x for half of distance between two plates _P=x _M-Δ cos δ and y _P=y _M-Δ Sin δ, and the coordinate of corresponding points P ' is on the hogback plate: x _{P '}=x _M+ Δ cos δ and y _{P '}=Y _M+ Δ Sin δ, wherein, δ is angle corresponding with angle ξ for every bit M, and ξ has given definition in the above when B is discussed.

For example so just can use certain class table to determine two relative oblong surface with suitable calculation procedure pointwise.As mentioned above, when making the actual inner surface of two plates with respect to two " substantially " buttocks, so the difference of determining can be used to define presumable in concave surface, and middle concave surface is no matter the form in cross section still is the longitudinal section can be optional according to the mode that has nothing to do with the present invention.

In any case be obvious more below, because camber changes to the predetermined value the 2500-6000mm that is applicable to slab ingot in bottom circular arc district continuously from a value (this is suitable for installing the nozzle of submergence most thereby for horizontal the moving that is caused by vibration) of top approach infinity, therefore its advantage is to have avoided foundry goods to take a sudden turn in the initial workshop section of this danger, and still uncured at this initial workshop section medium casting, its center still is a molten steel.In fact, these zig zags not only may make peeling leave mold wall and reduce cooling effect and cooling uniformity, and the distortional stress that concentrates on a certain position can cause skin crack and inner molten steel is flowed out, thereby badly damaged Casting Equipment, this not only causes spillage of material, and causes equipment to stop work and waste man-hour.

Should see that the present invention is not limited to try to achieve definite required result of elliptic curve with above-mentioned computational methods.

Claims (9)

1. one kind is used for the mould of continuously cast slab, its two relative broad limits are by the copper coin (1 of hogback plate that is respectively water-cooled and soffit plate, 1 ') constitute, concerning each plate, all can define the basic surface that the inwall with plate meets like this, thereby with regard to this basic surface, under the situation that may have concave surface in, with this inwall one deviation can be arranged, wherein, the buttocks of described basic surface is a circular arc turn of bilge (A-B) in the bottom, its flexural center overlaps with the centre of oscillation of mould, radius is (R), it is characterized in that, the described buttocks of basic surface is made of some curves that are mutually fillet, from this bottom circular arc, the bending radius of described each curve increases along with the distance of leaving this bottom circular arc and reduces, tie point between the adjacent curve does not all have turning and discontinuity in twos, be almost infinity up to locating this radius on relative top (F), thereby the tangent line approximate vertical of curve herein, it is between bottom (A) and top (F) that the height of described point (O) is positioned at the buttocks two-end-point.

2. by the described mould of claim 1, it is characterized in that, these curves of buttocks that are formed in the vertical plane on the basic plane of template at described each curve are circular arc, its flexural center is the intersection point of the line of this end of arc of connection and adjacent circular arc flexural center, (A-flexural center B) overlaps with the centre of oscillation of this mould (O) up to described last circular arc, the central angle of each circular arc (α) all equates, from the flexural center (O of top first circular arc of described point (F) beginning ^IV) in passing through on the horizontal line of this point (F).

3. by the described mould of claim 2, it is characterized in that, it is infinitely great that the number of described circular arc is tending towards, thereby form an oval curve, its bending radius downwards decrescence, up to the bending radius (ρ) of continuous change (B) point and described last circular arc shaped portion (A-B) in abutting connection with the time reach the minimum of a value of corresponding described predetermined radii (R).

4. by the described mould of claim 3, it is characterized in that, described elliptic curve extends between the described summit (F) and point (B) of described basic buttocks, (F) is corresponding with the inlet side of mould on this summit, tangent line herein is vertical, and the bottom circular arc of the tangent line of ordering at B and adjacency (tangent line of A-B) overlap and relative horizontal line tilt an angle (90 °+ξ), angle (ξ) be negative value, it be by the horizontal line of point (O) with (O) and (B) put the angle of line.

5. by the described mould of claim 4, it is characterized in that, (A-F) is a section in the ellipse to described elliptic curve, this oval center of circle (O ') be located at point (O) with passing on the horizontal line of (F) on one side, this center of circle (O ') can be used as a flute card from marking the initial point of system, its axle (x) line (O '-F) on, this line (O '-length F) equals the minor axis (b) of described ellipse.

6. by the described mould of claim 5, it is characterized in that the ordinate (n) of the described point (O) that overlaps with the mould centre of oscillation is the ordinate (y at zero and described point (B) _B) between a negative value, and point (B) be circular arc (starting point of A-B), and this circular arc (A-B) has the identical center of circle (O).

7. by the described mould of claim 6, it is characterized in that the described ordinate (n) of point (O) equals (Y _B/ 2).

8. by claim 6 or 7 described moulds, it is characterized in that, if the whole height of mould be about 1m, (height of A-B) is got 100mm to then described final arc sections approximately, and this height can be regarded the poor of ordinate in the described coordinate system that two-end-point (A, B) is (O ') at initial point as.

9. by the described mould of arbitrary claim in the claim 3 to 8, it is characterized in that the coordinate (x of the point (M) of a series of arbitrary numbers of the oval buttocks of each Tong Guo calculating formation one between described two buttocks in the two basic buttocks of hogback plate and soffit plate _My _M) and determined, and described two buttocks can use following relational expression to be defined by the coordinate of the point (P) of soffit plate and the point of hogback plate (P '):

y _P=y _M-Δ cos δ; y _P=x _M-Δ sin δ and x _P,=x _M+ Δ cos δ; x _P,=y _M+ Δ sin δ, wherein, Δ equals half of distance between the described two basic buttocks, and δ changes and equals an angle at the described angle (ξ) that described point (B) locates with each point M oval in the middle of described for its value.

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