KR20030080076A - Process for repairing a crack resistant valve plate - Google Patents

Abstract

The present invention relates to a method for repairing a fireproof plate (1) with a spout (3) surrounded by a circle (C) of the center (4), the edges (15, 16, 17, 18) of the plate (1). At least a portion of) is deflected at an angle to optimally concentrate the fastening force around the adjustment region and the sprue.

Description

Repair method for crack resistant valve plate {PROCESS FOR REPAIRING A CRACK RESISTANT VALVE PLATE}

Slide gate valves are commonly used to control the flow of molten metal in steel manufacturing processes and other metallurgical processes. Such slide gate valves generally can be slidably moved underneath the fixed valve plate, as well as an upper fixed valve plate with a support frame and an orifice that mates with a tundish or ladle nozzle to guide the flow of molten metal. And a throttle with a metal guide orifice. In a slide gate valve used with a continuous mold mold, the lower stationary valve plate is likewise provided under a movable control plate with a flow guiding orifice, which is almost aligned with the upper stationary valve plate. The flow rate of the molten metal depends on the degree of overlap of the orifice of the movable movable control plate and the upper fixed valve plate. The movable throttle usually has the ability to regulate the flow of molten metal from both the front and rear edges of the orifice itself, and the ability to completely block the flow by connecting the orifice completely outside any overlap with the orifice of the fixed throttle. It is longer than the fixed throttle to give. Usually, the throttle plate is slidably operated between the fixed plates by the hydraulic linkage device.

The throttle plate and the fixed plate are respectively mounted in the lower recess and the upper recess, each of which is seated in the recess through a surface serving as its support surface and cooperates with another plate through its sliding or working surface. do.

Both the throttle plate and the fixed plate of such a slide gate valve are formed from heat resistant and corrosion resistant fire resistant materials such as aluminum oxide, alumina-carbon, zirconium oxide. However, despite the heat and corrosion resistance of such refractory materials, the severe thermomechanical stresses they are subjected to eventually result in some cracking. For example, in the manufacture of steel, each valve plate receives a temperature of approximately 1600 ° C. in the region immediately surrounding the flow guide orifice, but its outer edges only receive ambient temperature. The resulting large temperature gradient generates a large amount of thermomechanical stress as the area of each plate immediately surrounding the orifice expands at a rate substantially greater than the rest of the plate. This stress causes cracks to be formed that extend outwardly from the orifice of the plate in the radial direction. If the diffusion of these cracks is not suppressed, they extend to all of the outer edges of the valve plate and the valve plate is broken.

In order to prevent the spread of such cracks and thus the destruction of the valve plate, several solutions have been developed in the prior art. In the first attempt, an improved fastening mechanism was designed. The purpose of these fastening mechanisms is to apply sufficient pressure around the outer circumference of the valve plate so that cracks developed from the orifice do not diffuse to the edge of the valve plate. One such mechanism includes a frame with a threaded wedge that engages a corner portion of the plate, which is cut off at an angle that complements the angle of the wedge. Such a system is disclosed in DE-C2-3,522,134. While such frame and wedge-type fastening mechanisms are advanced, the inventors have found that there is a disadvantage in their construction that prevents the achievement of complete crack arrest capability. In general, the clamping force is not uniformly concentrated near the point where the largest amount of cracking occurs, i.e., the orifice where the thermomechanical stress is greatest. In addition, Applicants have generally found that the angular orientation of the truncated corners in such plates does not best prevent the spread of cracks as previously thought. Such suboptimal results stem from the fact that the crack formation is not evenly distributed at 360 ° around the orifice and is deflected along the longitudinal centerline of all valve plates, fixed or movable. The asymmetric distribution of such cracks around the plate orifices is believed to occur as a result of the longitudinal sliding operation of the throttle plate across the surface of the stationary plate.

U. S. Patent No. 5,626, 164 discloses a crack resistant valve plate, the shape of which is configured to prevent the formation and diffusion of cracks therein. The valve plate includes a predetermined axis, a molten metal guide orifice disposed along the axis, and a truncated corner portion for concentrating a fastening force toward the axis near the orifice, wherein each truncated corner portion crosses the axis line. Orthogonal to the line extending between the contact point to the slicing orifice and the intersection of the lines drawn parallel to the converging plate edge spaced from the converging plate edge by half the distance of the orifice width.

Publication WO-A1-98 / 05451 discloses a variant of this solution in which the angle between the sides of the plate is formed to extend the life of the plate.

Although the solution of US Pat. No. 5,626,164 has already made significant and clear advances over previously known solutions, Applicants have nevertheless attempted to optimize the plate shape.

It is clear that a valve plate shape is required in which the clamping force is concentrated in the most prone area of the valve plate in order to prevent any crack from maximizing. Ideally, the corners have a length sufficient to prevent the occurrence of unwanted local mechanical stresses at the corners.

International patent application WO 01/41956 overcomes or at least ameliorates all disadvantages associated with the prior art, or is a crack resistant valve plate for use in a slide gate valve, at least equal to the performance of the plates disclosed in US Pat. No. 5,626,164. An assembly is disclosed.

The publication relates to a fireproof plate for a slide gate valve, whose two sides can be surrounded by an elongated rectangle R parallel to its extension direction. The rectangle R has a longitudinal axis formed as its longest axis of symmetry and coincides with the preferred sliding trajectory of the plate. However, it is clearly understood that this concept of preferred slide trajectory is an essential feature of the plate according to this publication, and that this plate may slide in the gate valve according to a direction other than the optimal or preferred direction. The plate has an orifice (guiding hole) for guiding the molten metal. The orifice is most often circular and is more commonly surrounded by a circle C of diameter φ.

For construction, the rectangle R is divided into four quadrants by two vertical lines intersecting at the center of the circle C, one of the vertical lines extending in the middle between the parallel sides of the rectangle R. do. Each quadrant intersects the diagonals. The diagonals (D1, D3, D5, D7) connect the center of the circle (C) to the corner of the rectangle (R) and the diagonals (D2, D4, D6, D8) Connect the sides of the rectangle (R) with adjacent intersections of vertical lines intersecting at the center of C).

The hot water can be placed in the center of the plate, but most often it is deflected along the longitudinal axis so that adjustment is made in a longer area. The spouts may also be slightly deflected along an axis perpendicular to the longitudinal axis.

The plate has an angled deflection (represented by the truncated corner portion of the rectangle R) in order to concentrate the clamping force near the orifice and toward the adjustment region to prevent the formation and spread of the crack.

According to International Patent Application WO 01/41956, at least a part of the edge is formed as follows.

The edge furthest from the spout (and therefore closest to the control area) is deflected up to 5 ° from the diagonal direction not intersecting each corner.

The edge closest to the spout (and hence farthest from the control area) is

(Iii) perpendicular to the diagonals intersecting each corner;

(Ii) different diagonal directions in each quadrant

(Iii) an intermediate direction between said directions (iii) and (ii)

Is deflected up to 5 ° from either direction.

Applicants have determined that the shape of such plates optimally concentrates the clamping force in two different areas of the plate. On the one hand, the control area is kept in a compressed state to prevent the appearance of cracks in that area, and on the other hand, the outer periphery of the mouth is also kept in a compressed state to prevent the spread of cracks emitted from the mouth.

Applicants have realized that the newly designed plates are extremely advantageous. First, much less cracks were observed. Second, even if cracks still occur, the cracks do not diffuse to the plate edges, resulting in significantly reduced air inflow. Thirdly, when the plate according to this European application is used in combination with a suitable fastening device, cracks (if any) occur only in acceptable areas. That is, cracks do not occur in the control region, but directly in the region between the spout and the nearest edge.

An additional advantage of this plate is that very few cracks are observed, so that the plate can be easily repaired quickly after being used. For this reason, the present invention is concerned with the repairing method of the used plate disclosed in WO 01/41956.

The plate may be symmetric about its longitudinal axis, but in a preferred embodiment said plate is not symmetric about the longitudinal axis.

Because of this asymmetry, the plate can only be mounted at one point in the upper concave and at one point in the lower concave, so that the support surface of the plate slides or acts if the plate passes from one point to another if the plate is to be reused. Becomes

The plate has only four edges as above but may have more edges to prevent acute angles. In such a case, the additional edge may be (or absent) parallel and / or perpendicular to the longitudinal axis.

It should be understood that it is not necessary that the plate is polygonal. In contrast, when fastening bands are used around the plate, such fastening bands can exert local mechanical stresses (which may change into cracks) on the vertices formed by the adjacent edges. Therefore, it is advantageous that the corner portion is curved.

The present invention generally relates to a repair of worn valve plates for use in slide gate valves that control molten metal flow, and more particularly to valve plates that are resistant to cracking resulting from thermomechanical stresses.

1 and 2 are plan views of International Publication No. WO-A1-01 / 41956.

In a preferred embodiment, only some of the edges satisfy this limitation. More preferably, the remainder of the edge consists of a curve connecting the edge portions, most preferably the relaxation radius of the edge.

It is also to be understood that the meaning of "plate" in the scope of the present invention is an (fixed or movable) assembly plate such as a monoblock nozzle plate, a monoblock inner nozzle plate, a monoblock tube plate, or the like.

Accordingly, the present invention relates to a method of repairing a worn fireproof plate of a slide gate valve, the fireproof plate being surrounded by an elongated rectangle R having two sides parallel to its longitudinal direction, the rectangle being this And a sprue located eccentrically between the parallel sides of the rectangle R and surrounded by a circle C, the rectangle R being defined by two vertical lines intersecting at the center of the circle C. Divided into four quadrants, one of which extends in the middle between the parallel sides of the rectangle R, each quadrant intersecting the diagonals D1, D2 and D3, D4 and D5, D6 and D7, Each having a D8), the corners of the rectangle R are cut and replaced by the beveled edges, the direction of at least some of these edges furthest from the mouthpiece being deflected up to 5 ° from the diagonal direction not intersecting each corner portion. High,

The direction of the edge closest to the mouthpiece is

(Iii) perpendicular to the diagonals intersecting each corner;

(Ii) different diagonal directions in each quadrant

(Iii) an intermediate direction between said directions (iii) and (ii)

Is deflected up to 5 ° from either direction.

Any suitable repair method may be used. It is to be understood that, precisely, the special crack resistance allows these plates to be repaired easily, quickly and efficiently.

In general, the repair method includes repairing the cracks with a mortar, such as REFRACOL 620 PL 45, that can resist molten steel, such as mortar, preferably mortar phosphate.

If necessary, it may be necessary to constantly polish the surface of the plate, for example, to remove the steel remaining on the surface of the plate before repairing the cracks. Any conventional technique may be used, such as polishing, sanding, water spray blasting, and the like.

Once the crack has been repaired, excess mortar is removed and the plate is dried. Drying is carried out in an oven at ambient temperature for at least 4 hours, preferably at least 8 hours or for example at 120 ° C. for 1 hour.

The plate can then be cured. This curing step may be carried out at 350-450 ° C. for 1 hour. In a variant, curing may also occur during use of the repaired plate if subjected to high temperatures in use.

In certain embodiments, the plate is preheated at, for example, about 80-120 ° C. so that the mortar penetrates deep into the crack and quickly sets.

In another embodiment, the mortar includes a hardener to set quickly even at ambient temperature.

Repairs can also be made if the ball is damaged. In general, a tubular object (eg, a pipe, rod or mandrel) with a diameter approximately similar to the original diameter of the tap is engaged in the tap. The perimeter of the tubular object is repaired, dried (usually the same as used for the cracks), dried and finally cured.

In a variant, the hole is also drilled (preferably coaxial with the original taphole and preferably at least 50% larger than the original diameter of the taphole), the insert is placed in the newly drilled hole and the mortar is applied. The insert is preferably made of a material that is at least as resistant as the original material of the plate. It may be convenient to provide protrusions or holes in the outer wall of the insert such that the mortar and the insert penetrate each other. It is also possible to use stepped inserts formed as two (or more) superimposed coaxial tubes having the same inner diameter but different outer diameters.

Referring now to FIG. 1, like numbers refer to like elements throughout the drawings. Disclosed herein is a valve plate 1 for use in a slide gate valve of the type used to regulate the flow of molten steel or other metal from tundish to mold or from ladle to tundish.

The valve plate 1 comprises an orifice 3 (pourer) for pouring molten metal flow. The spout 3 is surrounded by a circle C of the center 4. FIG. 1 shows a valve plate with a non-circular water tap, and FIG. 2 shows a valve plate with a spout 3 corresponding to the circle C. FIG.

1 and 2, a rectangle R is shown. The rectangle R surrounds the valve plate 1, the longest side of which is parallel to the slide trajectory of the valve plate in the slide gate valve. For the construction it is necessary to draw two vertical lines across the center 4 of the circle C and parallel to the short and long sides of the rectangle R. Accordingly, these vertical lines form four quadrants of the rectangle R. Each quadrant has an intersecting diagonal line, the diagonal lines D1, D3, D5, and D7, which place the center (4) of the circle (C) at the four corners (7, 8, 9, 10) of the rectangle (R). And diagonal lines D2, D4, D6, D8 connect adjacent intersections 11, 12, 13, 14 of the vertical lines 5, 6 with the sides of the rectangle R.

The edges of the valve plate are in particular configured to concentrate the fastening force in the adjustment region, ie the edges 15, 16 which are furthest from the mouthpiece 3 and thus closest to the adjustment region are quadrants comprising said edges. Have at least a portion (to which the tightening force is applied) parallel to the diagonal (D2 or D4) of.

1 and 2, at least part of the edge 15 is parallel to the diagonal D2 and at least part of the edge 16 is parallel to the diagonal D4. In FIG. 1, the entire edges 15, 16 are parallel to the diagonals D2, D4, while in FIG. 2 only a part of the edges 15, 16 are parallel to the diagonals D2, D4.

The edges of the valve plate, particularly the edges 17, 18 closest to the spout 3, which are specifically configured to concentrate the fastening force around the spout 3, are arranged on the diagonal D5 or D7 of the quadrant which comprises this edge. It may be formed perpendicularly or in other words parallel to the direction 19 or 20 formed perpendicular to the diagonal D5 or D7. This embodiment is shown by the edges 17, 18 of FIG. 2, which are perpendicular to the diagonals D5, D7, respectively.

Alternatively, these edges 17, 18 may be formed at the diagonals D6 or D8 of the quadrant containing these edges, as shown by edges 17, 18 of FIG. 1 perpendicular to the diagonals D6, D8. It may be formed parallel to the.

In another variant, the edges 17 and 18 may be deflected in a direction comprised between the two directions described above.

The edges 15, 16, 17, 18 may contact each other to form a quadrilateral plate 1 formed by connecting diagonals D2, D4, D6, D8. It is clear that in order to avoid mechanical stress, the prevention of the corner portion at which such tip is formed is preferable. Thus, the edges 15, 16, 17, 18 are preferably not in direct contact. The edges may be separated by a straight line, preferably parallel to the sides of the rectangle as shown in FIG. 1.

More preferably, the edges are separated by a relaxation curve.

In FIG. 2, the edges 15, 16 and the edges 17, 18 are connected by a relaxation radius 21, 22.

The main variable that determines how the edges concentrate the clamping force to prevent cracking is the deflection of the edges 15, 16, 17, 18. The position of the edge with respect to the spout 3, ie the position of the edges 15, 16, 17, 18 along each of the diagonals D1, D3, D5, D7, is of less importance for that criterion. However, the edges 15, 16, 17, 18 are preferably not too long to prevent mechanical stress due to the corners at which the tip is formed, and not too short to efficiently concentrate the clamping force at the required points.

Thus, the edges closest to the adjustment area, ie the edges 15 and 16 (or their protrusions), are included in 1/8 to 3/8 and 5/8 to 7/8 of the length of the short sides of the rectangle R, respectively. It is preferable to cut the area | region of the short side of the rectangle R to become.

This requirement is of less importance on the other side of the valve plate (ie the side whose edge is closest to the spout), so that the edges 17 and 18 (or their protrusions) are 1 / of the length of the short side of the rectangle R. It is preferable to cut the area | region of the short side of the rectangle R contained in 10-9 / 10.

International Patent WO 01/41965 discloses a method for determining whether a plate is constructed or not according to the technique.

Claims (7)

A method of repairing a worn refractory plate (1) for a slide gate valve, wherein the refractory plate is surrounded by an elongated rectangle (R) whose two sides are parallel to its longitudinal direction, said rectangle being of this rectangle (R). A sprue 3 eccentrically located between the parallel sides and surrounded by a circle C of the center 4, the rectangle R intersecting at the center 4 of the circle C Is divided into four quadrants by two vertical lines (5, 6), one vertical line (6) of which extends in the middle between the parallel sides of the rectangle (R), each four In the quadrant, there are intersecting diagonal lines (D1, D2 and D3, D4 and D5, D6 and D7, D8), and the corner portions 7-10 of the rectangle R are cut off to the inclined edges 15-18. At least part of the edges 15, 16, which are furthest from the mouthpiece 3, are replaced by a diagonal direction that does not intersect each corner portion. In the repairing method, which is biased against 5 °, The direction of the edges 17 and 18 closest to the mouthpiece 3 is (Iii) perpendicular to the diagonals intersecting each corner; (Ii) different diagonal directions in each quadrant (Iii) an intermediate direction between said directions (iii) and (ii) A method for repairing a deflection of up to 5 ° from either direction. The method of claim 1 including repairing the crack with mortar. The method according to claim 1 or 2, a) perforating a hole that is approximately coaxial with the original spout and is at least 50% larger in diameter than the original spout; b) placing an insert in the perforated hole, c) repairing with mortar between the insert and the wall of the drilled hole Repair method comprising a. The repair method according to claim 2 or 3, wherein the mortar is mortar phosphate. The method of any one of claims 2 to 4, comprising drying the repaired plate. The method of any one of claims 2 to 5, comprising curing the repaired plate. A plate obtainable by the method according to any one of claims 1 to 6.