FR2594728A1 - Insert intended to be implanted in the plates of continuous-casting tundishes and device for machining a frustoconical bore in the said plates - Google Patents

Abstract

The invention relates to an insert intended to be implanted in the stationary and movable plates of slide or rotary tundishes of a continuous-casting installation in the field of metallurgy, as well as to a device for machining frustoconical bores, particularly for the overhaul of the tundish plates for the positioning of the said inserts. According to the present invention, the outer profile of the inserts for overhauling the tundish plates is frustoconical. The device for machining a frustoconical bore is composed of a gripping handle 29, intended to be fastened in a rotational driving mechanism, such as a drill chuck, and of an axial body 30 provided with tangential bearing surfaces for the positioning of cutting tips (pads) 31 arranged along the generatrices of the axial body 30 with a certain tilt relative to the axis of rotation 32, in order to form the slope of the cone. Moreover, the end of the tool is formed by a tool for coring 34, formed from a skirt 35 whose periphery is fitted with diamond-charged cutting tools 37 for producing the cylindrical machining in the plate.

Description

 The invention relates to an insert intended to be installed in the fixed and mobile plates of slide or rotary distributors of a continuous casting installation in the steel industry as well as a device for machining frustoconical bore in particular in said distributor plates. It will particularly find its application for the repair of distributors in steel mills.

 We know the continuous steel casting facilities, composed in particular of a melting ladle, provided in its lower part with a device for discharging molten metal. This device notably comprises a nozzle opening into a flow distributor, whose role is to direct the molten steel from the ladle into different ingot molds.

 However, to control the evacuation of molten metal from the ladle, it is necessary to set up a distributor which acts as a stop valve during the production of the steel and which is then opened to allow the flow of molten steel into the nozzle.

 Two types of distributors are mainly used, these are drawer or rotary distributors.

 The distributors consist of a fixed plate and a movable plate. Each of them is provided with a steel flow orifice. When the positioning of the fixed and movable plates respectively called stator and rotor is such that the orifices coincide, a corridor is created for clearing the molten steel and the valve is thus in the open position. On the other hand, when the positioning of the stator and the rotor is such that the orifices of each of them do not coincide, there is blockage of the steel flow channel and the valve is in the closed position.

 The fixed and movable plates are made of refractory materials, however, wear and tear on the pouring orifices is very quickly recorded, which causes degradation of the plates. Since the caliber of the casting orifice makes it possible to determine the flow characteristics of the molten steel, any wear on the plates is detrimental to the proper functioning of the continuous casting installation. It is therefore necessary to repair the plates.

 The repair method currently used consists in enlarging in the stator and the rotor, the orifice (s) through which the steel passes to eliminate all the degraded surface. This operation is carried out using a diamond-shaped tool in the shape of a bell which allows a circular cut to be made in the plates. In the bore thus machined, there are sealed plugs made of refractory material called "insert" which allow to recalibrate the flow orifice of the molten steel. The inserts are rectified on each of the faces of the rotor and the stator so as to obtain perfect flatness of the contact surface of the two adjacent parts in the distributor.

 The two types of inserts currently used are of the circular crown type or circular crown with shoulder.

 Different drawbacks are linked with each of the types of insert previously mentioned. In particular, for the installation of the sealing joint of the insert, it is necessary to leave a clearance between the insert and the plate. However, due to this large dimension play, it becomes very delicate thereafter to achieve perfect centering of the insert in the bore formed in the plate. This decentering favors the destruction of the joint by the molten steel, which considerably shortens the life of the distributor.

 The inserts with shoulder require a double machining for the embedding of the shoulder in the plate and do not offer greater facilities for centering, except that they benefit from an axial stop.

 In conclusion, repairing the distributors, which is a long and delicate operation in terms of machining, is only unsatisfactory because of the relatively limited life of the repaired distributor.

 The main object of the present invention is to present an insert intended to be installed in the fixed and mobile plates of the distributors of whatever type, with a view to ensuring its repair by recalibration of the pouring orifices. The new proposed insert model offers the advantage of self-centering in the plate and therefore, the variations in thickness variation of the sealing joint are eliminated. The service life of the repaired plates is therefore significantly improved with respect to the current state of the art.

 Another object of the present invention is to present a device for machining a frustoconical bore, in particular in distributor plates for the installation of inserts according to the invention. It is a tool which offers the advantage, according to a preferred embodiment thereof, of carrying out the machining in a single operation. Consequently, economically, its implementation is extremely rapid.

 Furthermore, the tools can be installed in a simple drill and does not require any specialized machine tool. The machining device of the present invention can therefore be used in different workshops, without any difficulty.

 Other objects of the present invention will emerge during the description which follows which is however given only for information.

 The insert intended to be installed in the fixed and mobile plates of slide or rotary distributors of a continuous casting installation in the steel industry, said insert comprising a central orifice for the passage of molten metal is sealed in bores made in the fixed plate called stator and the movable plate called rotor, using a refractory adhesive and is characterized by the fact that it has a profile which ensures a radial centering in the bore of the plate during its implementation in the latter.

The device for machining frustoconical bores, in particular in distributor plates for fitting inserts according to the invention, is characterized in that it is composed
- a gripping shank intended to be fixed in a rotary drive mechanism such as a drill chuck,
- An axial body comprising at least one tangential bearing for the establishment of at least one cutting pad arranged along a generatrix of the axial body with a certain inclination relative to the axis of rotation.

The invention will be better understood on reading the following description accompanied by attached drawings, among which
FIG. 1 shows diagrammatically, in section view, a continuous steel casting installation,
FIG. 2 represents, in section view, a distributor at the level of the flow orifice, repaired with inserts according to the current state of the art,
FIG. 3 shows diagrammatically, in section view, a distributor repaired with inserts according to the present invention,
FIG. 4 shows an alternative embodiment of FIG. 3,
FIG. 5 shows diagrammatically an axial section view of a device for machining frustoconical bores according to a preferred embodiment thereof,
FIG. 6 represents a sectional sectional view of the device for machining a frustoconical bore of FIG. 5,
FIG. 7 shows a detail of the device of the invention shown in FIG. 6, seen according to arrow VII.

 The present invention relates to an insert intended to be installed in the fixed and mobile plates of slide or rotary distributors of a continuous casting installation in the steel industry as well as a device for machining frustoconical bores in particular in distributor plates.

 The present invention has been more particularly developed in the steel industry where a large number of refractory materials is used. However, this application is not limiting and the present invention may also be used in other fields where the machining of hard materials must be practiced.

 Figure 1 shows schematically a sectional view of a continuous steel casting installation. This installation comprises a pocket (1) in which the molten steel (2) is produced. The pocket (1) is made of a refractory insulator and its bottom is crossed by a collector (3) which opens onto a distributor (4).

 This distributor consists of a fixed plate (5) called the stator and a movable plate (6) called the rotor. The distributor opens into a nozzle (7) which, in the case of the figure, is formed of the elements (8) and (9) connected.

 The nozzle opens into a distributor (10) intended to contain the molten metal and whose role consists in conveying the liquid steel towards ingot molds via valve collectors (11), valves (12), nozzles casting (13).

 Although made of suitable refractory material, the fixed plate (5) and the movable plate (6) of the distributor (4) are quickly put out of use due to the significant erosion which manifests itself at the orifices (14) and ( 15) flow of molten metal.

 Given that the degradation is localized and that the systematic replacement of these plates is very expensive, it is necessary to proceed with the repair of said plates.

 For this purpose, the method currently used consists in enlarging, in the stator (5) and the rotor (6), the orifices (14) and (15) for passage to eliminate all the degraded surface, then to seal in the new bores. machined, inserts with calibrated flow orifice and to rectify the faces of the stator and rotor which are in contact in the distributor (4).

 Figure 2 shows schematically in section a distributor (4) -repaired with the use of inserts (16) and (17) according to the current state of the art.

 The two models of inserts currently used are of the circular crown type, as illustrated in FIG. 2 under the reference (16) or of the circular crown type with shoulder, as illustrated in FIG. 2 under the reference (17). . The internal diameter of the flow orifices (14) and (15) respectively of the crowns (16) and (17) corresponds to the diameter of the initial steel flow orifice.

 The main drawbacks of the insert models illustrated in FIG. 2 reside on the one hand in the infiltrations of molten metal which occur in the thickness of the sealing joints and on the other hand in the difficulty of centering the inserts.

 They are sealed in their respective housing by means of a refractory adhesive (18) poured into the gap formed between the bore made in the plates (5) and (6) and the outside diameter of the inserts (16) and (17 ).

 On the other hand, in order to reinforce the solidity of the sealing of the non-shouldered insert (16), anchoring grooves (19) are provided.

 When the setting of the adhesive is finished, the faces (20) of the stator (5) and rotor (6) are rectified to ensure a perfect seal at their contact.

 During operation, under the effect of repeated thermal shocks which cause shrinkage and expansion, crevices quickly arise in the thickness of the joints since it is very difficult to obtain a refractory adhesive having a coefficient of expansion identical to that of refractory pieces.

 Always under the action of repeated thermal shocks, the crevices increase in volume and number because molten metal infiltrates them. Gradually, the inserts become "leaky" and they can even loosen if the mechanical stresses are high.

 Among the drawbacks encountered, it should be noted that in the open position, leaks of molten metal occur at the lower periphery of the insert (16).

 In addition, under the thrust exerted by the molten metal overcoming the stator (5), the insert (16), if it is loosened, comes to rest on the rotor (6) which abnormally increases the mechanical work of the distributor (4). It is the same if the insert (17) came to rest on the stator (5) under the influence of the thrust that could exert the molten metal under the shoulder (21) of the insert (17) .

 When, for example, the insert (16) is unsealed and the insert (17) is eroded, as illustrated in FIG. 2 under the reference (22), it sometimes happens that the distributor (4) is blocked. in the intermediate position as a result of a partial interpenetration of the two inserts when the dispenser (4) is opened or closed.

 According to the present invention, the proposed insert has a profile which provides it with radial centering in the bore of the distributor plate when it is placed in the latter. The radial centering of the insert, during its simple positioning in the plate, represents an important advantage since it makes it possible to guarantee the uniformity of the thickness of the adhesive sealing joint and perfect centering.

 Figure 3 shows a sectional view of the dispenser (4) at the placement of inserts (23) and (24) according to the present invention. The inserts (23) and (24) have a frustoconical external profile complementary to the frustoconical bores of the plates (5) and (6). In the example chosen, the inserts (23) and (24) have the same base diameter and an equal taper.

 The thickness of the sealing joint (25) and (26) used could be considerably reduced compared to that of FIG. 2. The sealing joint only serves to fill in the imperfections in the surface condition.

 The faces (27) of the stator (5) and rotor (6) are rectified to obtain a contact flatness.

 As a result of the reduction in the thickness of refractory adhesive, the disadvantages previously encountered are eliminated. Due to the taper, the simple placement of the inserts in the plates causes self-centering.

 Figure 3 shows a first arrangement of the frustoconical inserts (23) and (24). However, other arrangements could be envisaged, such as in particular those illustrated in FIG. 4.

 The only difficulty in implementing the present invention lies in the machining of the frustoconical bore in the distributor plates.

 To this end, the present invention provides a device for machining frustoconical bores, in particular in distributor plates for the installation of inserts according to the invention.

The machining device (28) consists of
- a gripping tail (29) intended to be fixed in a rotary drive mechanism. Preferably, it is a drill chuck; however, other machine tools may be used, such as a milling machine or the like.

 - an axial body (30) comprising at least one tangential bearing for the installation of at least one cutting pad (31) arranged along a generatrix of the axial body with a certain inclination relative to the axis of rotation (32).

Said inclination serves to give the taper to the bore.

 The tool described above allows from a cylindrical bore to give a certain taper to its inner wall to allow the installation of an insert with frustoconical external profile.

 However, preferably, the machining device (28) comprises fixing means (33) to allow the installation of a cylindrical machining tool (34) centered at the end of the axial body (30).

 FIG. 5 illustrates such a cylindrical machining tool of the core type formed by a tubular skirt (35) the lower edge of which is lined with diamond pads (37) supported. The thickness of the pellets (37) is greater than that of the skirt, which allows the tool to penetrate the plate to be machined so as to carry a part of the plate and to form a cylindrical bore.

 The upper part of the skirt (35) is provided with a flange (36) comprising a shoulder (38) which is received in a circular groove (39) produced in the axial body (30) so as to center the two tools.

 In this way, the production of a frustoconical bore can be done in a single operation because, after having made the cylindrical cut using the coring tool, the cylindrical bore can be directly attacked by the tool d 'tapered machining (28). No centering is to be carried out between the two operations, which saves time and great machining precision.

 Preferably, the positioning of the cutting pads (31) for producing the frustoconical bore, on the surfaces of the axial body (30), is adjustable.

 Clamping of the cutting pads (31) on the bearing surfaces of the axial body (30) is ensured by means of two screws (40) passing through oblong holes (41) made in the support of the cutting pads (31).

 The oblong holes allow a certain movement of the cutting pads (31) which can thus be moved to catch up with their wear or to modify the taper of the bore to be produced.

 Preferably, the positioning of the cutting pads (31) is adjusted by tightening the screws (40) while the tool (28) is placed in a frustoconical template which encloses and positions the cutting pads (31).

 Preferably, the axial body (30) of the tool (28) is of frustoconical shape having a star-shaped section as illustrated in FIG. 6, the branches of which have a bearing surface (42) for the cutting inserts ( 31). The diamond cutting inserts (31), for example six in number, are regularly distributed around the axial body (30).

 In a preferred embodiment of the invention, the cutting inserts (31) will have a trapezoidal face profile, as shown in FIG. 7. This advantageous arrangement makes it possible to have a larger attack surface in the lower part (43 ) of the plate (31) so as to increase the life of the latter. In fact, when the tool is working, this lower zone (43) works more than the upper zone (44) due to the truncated cone bore.

 The cutting diameter of the cylindrical machining tool (34) is greater than the leading diameter of the frustoconical machining device so as to allow penetration and centering of the latter in the bore made by the tool to core.

 Other implementations of the present invention, within the reach of ordinary skill in the art, could also have been envisaged without departing from the scope thereof.

Claims (10)

 1. Insert, intended to be installed in the fixed and mobile plates of spool or rotary distributors of a continuous casting installation in the steel industry, said insert comprising a central orifice for the passage of molten metal, sealed in bores made in the fixed plate called the stator (5) and the movable plate called the rotor (6) using a refractory adhesive, characterized by the fact that it has a profile which provides it with radial centering in the bore of the plate during its installation in the latter.  2. Insert according to claim 1, c a r a c t é r i sé in that it has a frustoconical external profile complementary to the frustoconical bore of the plates (5) and (6).  3. Device for machining frustoconical bores, in particular in distributor plates (4) for the insertion of insert according to claim 2, c a r a c t é r i sé in that it is composed  - a gripping tail (29) intended to be fixed in a rotary drive mechanism such as a drill chuck,  - an axial body (30) comprising at least one tangential bearing for the installation of at least one cutting pad (31) disposed along a generatrix of the axial body (30) with a certain inclination relative to the axis of rotation (32).  4. Machining device according to claim 3, c a r a c t é r i sé in that it has fixing means to allow the establishment of a tool  cylindrical machining (34) centered at the end of the axial body  (30).  5. Machining device according to claim 3,  This is because the positioning of the  cutting pads (31) on the bearing surfaces of the axial body is  adjustable.  6. Machining device according to claim 5, c a r a c t é r i sé in that the tightening of the cutting discs (31) on the surfaces (42) of the axial body (30) is  secured by two screws (40) passing through  oblong holes (41) made in said pads (31).  7. Machining device according to claim 6, c a r a c t e r i ed by the fact that the adjustment of the positioning of the cutting pellets (31) is ensured by  tightening the screws (40) while the tool (28) is placed in a frustoconical template.  8. Machining device according to claim 3, characterized in that the axial body (30) is of frustoconical shape, having a star section whose branches have a bearing surface (42) for the pads. cutting (31).  9. Machining device according to claim 4,  c a r a c t é r i s é by the fact that the cylindrical machining tool is of the core type whose cutting diameter is greater than that of the device for machining frustoconical bores.  10. Machining device according to claim 8,  it is because it has platelets  cutting (31) diamonds, regularly distributed around the  axial body (30).