RU2085327C1 - Crystallizer for continuous steel slab casting machine - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: crystallizer has protective surfacing formed as portions of wear-resistant material in lower parts of working walls. Protective surfacing imparts increased abrasive wear resistance to working walls. Surfacing is effectuated by manual welding. Protective portions do not hinder mechanical working of crystallizer. Construction of crystallizer allows differentiated protection in maximum wear zones to be provided. EFFECT: increased efficiency, simplified construction and enhanced reliability in operation. 4 dwg

Description

 The invention relates to metallurgy, in particular the continuous casting of steel, and in particular to the design of molds.

 Known molds equipped on the inner (working) walls with grooves filled with refractory material (ed. St. USSR N 499950, class B 22 D 11/04, 1976).

 This design allows to reduce the abrasive and thermal wear of the mold.

 However, in this design, heat dissipation from the surface of the workpiece is deteriorated, and the mold service conditions are complicated, since the material filling the grooves of the mold working surface has a volume expansion coefficient different from the material from which the mold is made.

 This disadvantage was partially eliminated in the mold (Austrian patent N 375571, class B 22 D 11/04, 1984), in which a wear-resistant coating is applied only to the lower part of the working walls, and the upper part, where the maximum heat dissipation should be, does not have a protective coating .

 This solution improves the conditions of heat removal from the upper part of the cast billet and reduces abrasive wear in the lower. However, a continuous wear-resistant coating nevertheless worsens the tap, and its small thickness leads to a relatively rapid wear of the coating.

 Closest to the proposed is a mold (ed. St. USSR N 880615, class B 22 D 11/04, 1981), in which the walls are protected from abrasion by inserts of stainless steel in the grooves in the working walls of the mold.

 The disadvantage of this invention is that between the inserts there are continuous sections that are not protected by wear-resistant material.

 The purpose of the invention is to increase the service life of the mold and at the same time improve the cooling of the ingot.

 The goal is achieved by the fact that on the working walls of the mold there are recesses in the form of deep-groove holes with bushings pressed into them, the cavity of which is filled with wear-resistant metal by surfacing, and the length is 35-30% of the mold wall thickness, while the recesses are made in the middle part of the mold walls in a checkerboard order, and along the edges of narrow walls linearly 1/4 of the height from the bottom of the mold.

 An advantage of such a mold is that the heat sink surface is made mainly of copper or a copper-containing alloy, i.e. has good thermal conductivity.

 However, in the zone of greatest abrasive wear (bottom of the working surfaces of the mold) are deposited sections of wear-resistant steel.

 The abrasive (abrasive) effect of the cast billet is largely compensated by the presence of such sections, and the relatively large depth (30 - 35% of the wall thickness) allows the walls to be processed after the mold is out of order, while the previously mentioned analogues due to the small thickness the overlay protective layer can be subjected to this operation without removing the protective layer.

 To eliminate local wear between the weld sections, the latter are placed in horizontal rows, and the rows are offset relative to each other ("checkerboard" order). Thus, a line drawn parallel to the axis of the mold along the edge of the working surface will intersect several deposited sections, i.e. almost the entire work surface has abrasion protection.

 The degree of increase in the resistance of the mold will depend on the material selected for surfacing, it should be borne in mind that, in addition to wear resistance, the deposited material must have good corrosion resistance at high temperature.

 In FIG. 1 shows a crystallizer; in Fig.2 node 1 in Fig.1; figure 3, 4 of the weld section. The mold (figure 1) consists of wide walls 1, narrow walls 2, deposited sections 3.

 The weld section (figure 2) is a pressed sleeve 4 made of stainless steel, surfacing material 5 (bronze or stainless steel).

 The location of the deposited areas on the working surface is staggered and depends on the type of mold (examples) and the type of installation on which the mold is installed. The same factor is also decisive for the choice of the size of the deposited areas and the pressed bushings.

 This design of the mold allows you to save effective heat removal from the ingot with less abrasive wear.

 In addition, such protection can also take into account the deviation of the zones of greatest wear, sometimes observed for each specific mold in certain plants due to the technical or technological features of their manufacture and operation, i.e. where wear is higher, the area of the deposited areas may be larger, and vice versa. With differentiated wear, this can have a decisive influence on the optimal ratio of the cost of manufacturing the mold and its resistance.

 Example 1. The narrow wall of the crystallizer vertical slab UNRS (Fig. 2), size 1200 • 400 mm, has 39 holes with a diameter of 32 mm, bushings made of stainless steel with an internal diameter of 16 mm are pressed in. The sleeve through the hole is welded to the mold, while the hole is completely filled with surfacing metal.

 Sleeves with surfacing are located on the surface of the wall as follows.

 The centers of the bushings are along the lines drawn parallel to the edges of the wall at a distance of 30 mm below, the distance between the centers of 44 mm along the lower edge of the wall, the rest are located on arcs with different radii drawn from the center lying on the axis of the wall, at a distance of about 1/4 of the height mold from the bottom edge, the pitch between the radii is 1.1 1, 6 of the diameter of the sleeve, the staggered arrangement along the edges at a distance of 30 mm from the edge is linear (figure 3).

 Similar devices are fused to the same height on a wide wall in a checkerboard pattern, with the location in the middle part of the wall corresponding to the location in the middle part of the narrow walls, and the location of the edge weld on 2 pieces. less in height than on a narrow wall.

 Example 2. A mold of radially curved UNRS with a height of 1220 mm, a narrow wall width of 200 mm; differs from the vertical URS in that the side wall has a certain radius of curvature (in this case, 10 m, see Fig. 4).

 Adjacent to the edges of the walls of the plot are fused analogously to example 1, and the step between the centers of the bushings mounted on the zone adjacent to a large radius is chosen arbitrarily within 1.20 1.75 of the diameter of the bushings. From the center of the axis of the sleeve, a radius is drawn to the center of curvature of the mold, and its intersection with a line parallel to the edge of a small radius and 30 mm away from the latter gives the center of location of the opposite sleeve (“symmetric” of the first).

 At a distance of about 1/4 of the mold height along the axis of its wall, a point is selected through which a segment of radius is drawn to the center of curvature of the mold. The centers of two opposite opposite edges of the bushings are connected by a segment, from the middle of which a perpendicular is drawn to intersect with a radius segment, and the intersection point will be the center of the arc on which the axis of the surfaced bushings are located.

 The bushings are staggered on these arcs ("checkerboard radial" arrangement).

 A wide crystallizer wall is manufactured analogously to example 1. This arrangement allows you to cover a large area with protective surfacing at the edges of the faces (where the wear is greatest), and less in the zone of moderate abrasive wear.

 Example 3. The narrow wall of the mold curvilinear slab installation with parameters similar to example 2.

 The lower edge and the edge adjacent to the larger radius are marked out as in example 2. Through the centers of the bushings, segments are drawn towards the center of curvature of the mold. On these segments at equal intervals (0.7 to 0.9 of the diameter of the bushings), their axes are staggered, and at the edges the number of cladding is 2 4 pcs. more than in the middle. The distance from the axis of the upper sleeve, located in the middle of the face, to the bottom of the mold is approximately 1/4 of its height.

 Wide edges are made analogously to example 1.

 Compared with molds, the walls of which are protected with special coatings (electroplating, etc.), the proposed one has the advantage that it can be manufactured in the same workshop and on the same equipment where the blanks for the mold walls are processed, i.e. no special coating area required.

 Existing protective devices in the form of dowels and longitudinal strips of wear-resistant material are inferior to the proposed one in that the mold equipped with longitudinal protective dowels (strips) can undergo local wear in the area between the dowels (deep scratch), which will lead to its premature failure.

 Thus, when casting certain grades of steel, the proposed mold design for certain types of structures of the UNRS may be the most suitable for use.

Claims (1)

 A mold for a slab installation of continuous casting of steel, comprising a housing and wide and narrow working walls, in the lower part of which are recesses, the cavity of which is filled with wear-resistant metal, characterized in that the recesses in the walls of the mold are made in the form of deaf holes with a length of 35 to 30% of the thickness of the mold walls , bushings are pressed into the recesses, the cavity of which is filled with surfacing metal, while the recesses in the middle part of the mold walls are staggered, and at the edges thin walls linearly to 1/4 of the height from the bottom of the mold.

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