FR2939781A1 - REINFORCEMENT FOR WIRE COIL FOR ADDITION OF SUBSTANCES IN A LIQUID METAL BATH. - Google Patents

Abstract

Reinforcement for holding a coil (1) of wire (3, 4) solid or filled for carrying out the addition of substances in a bath of liquid metal, comprising uprights (7) enclosing said coil (1) and whose the internal faces (9) come into contact with the outermost layer (10) of turns of the wire constituting said coil (1). Said internal faces (9) of said uprights (7) comprise, at least over a portion of their length, means tending to intensify the contact between these uprights (7) and the wire by increasing the adhesion between all or part of the turns (3, 4) of the last layer of turns (10) of said wire and the uprights (7) and / or maintaining all or part of the turns (3, 4) of the last layer of turns (10) of said wire in housings formed on said uprights (7).

Description

The invention relates to the treatment of liquid metal baths, and more particularly to the dispensing devices, in these baths of liquid metals, of additives in the form of son. It is now common, in metallurgy in general and in the iron and steel industry in particular, to make precise additions of substances, intended to constitute final metal alloying elements and / or to perform metallurgical treatment operations of the metal bath. by unwinding a wire in said bath. This wire may be full, that is to say entirely consisting of the metallic substance that is to be added. It may also be a cored wire, that is to say be made of a metal shell of a material compatible with the base metal of the bath (steel, copper or other), containing the substance or substances that are wants to add, this or these substances being in powder form. To be limited to the steel industry, it being understood that this field is only one example of those in which the technology of the unwinding of solid wire or cored wire is currently applied, we can cite as examples, far from being exhaustive: - The addition of solid aluminum wire, to deoxidize the steel by alumina formation and add a well-defined amount of aluminum to serve as an alloying element; the addition of flux-cored wire to pure calcium or, most often, to silicocalcium (alloy composed of about 2/3 by weight of silicon and about 1/3 by weight of calcium), to carry out modification and control of the composition of nonmetallic inclusions resulting from the deoxidation or reoxidation of liquid steel; it is thus possible to convert the inclusions of alumina into inclusions of aluminates or silicoaluminates of lime, which are liquid at the temperature of the molten metal; It is thus intended to prevent the casting nozzles of the tundish of the continuous casting machine from being gradually blocked during casting by solid alumina inclusions which would accumulate on the walls of the nozzles, to make possible the coalescence inclusions oxidized in the form of large drops that can easily decant, which improves the inclusion cleanliness of the final metal, and finally to confer remaining inclusions forms, compositions and mechanical properties favorable to a good behavior of the steel at its formatting and its use. Calcium can also combine with sulfur and help desulphurize steel and control residual sulphides.

In the remainder of the description, it is to be understood that yarn will be referred to, thus designating both solid and filled yarns, of all compositions and uses, the invention being equally applicable to both types of yarn. Conventionally, the solid or filled wire is initially wound in cylindrical coils on a cylindrical mandrel. It is unwound as and when needed. The axis of symmetry of these coils can be either horizontal or vertical. One of the advantages of this addition technique is the possibility of connecting the coils together and thus avoiding the interruption of the metallurgical treatment and handling each coil. The passage from one reel to another is thus an operation that does not require any intervention by the user at the moment when it takes place. This advantage is sometimes decisive for products that must be added to liquid metal baths at the very end of treatment, because this operation can not tolerate any delay or incident. A coil of wire is a continuous winding of superimposed layers of contiguous turns. The wire is thus wound around a mandrel (for example from left to right). The dimensions of this mandrel give the final coil its inside diameter and its width. Once the cylindrical surface of the mandrel is completely covered by a first layer of turns, a second layer of turns is wound in the opposite direction of the first bearing on it. The cycle continues until the desired outer diameter for the coil is obtained. The winding of the coil ends when the end of the thread of the last turn is on the same face as the origin (face where the winding started). In order to maintain this arrangement of turns correctly in place, the coil is generally packaged in a frame, generally metallic. The packaging consists of a pallet on which the coil rests and a metal frame that traps the coil. Amounts, for example four in number, come into contact with the last row of outer turns. These are the amounts that hold up the turns of cored wire. The reels are unwound from the inside (small diameter) outwards by a reeling installation which initially receives the free end of the first turn wound on the mandrel, so the innermost turn. The coils are connected to each other by means of a length of free wire from the last coiled coil. In the case of vertical coils, the two ends are located on the same face to allow the connection, the last outer turn of one being mechanically connected to the first inner turn of the second.

The unwinding takes place from top to bottom and then from bottom to top for a spool with a vertical axis, or from front to back and vice versa for a coil with a horizontal axis, in accordance with the winding direction of the windings described above. The successive unwinding of the rows of turns finally releases the row of outer turns. Once the outer end is reached, if it has been previously connected to the inner end of the next coil, the transition between the coils takes place without intervention. The use is therefore continuous. Examples of wire coils to which the invention may advantageously be applied have the dimensions given below: internal diameter of the coils of 500mm to 1000mm; - outer diameter of the coils from 800mm to 2500mm; - width of the coil (or height if the coil is vertical axis) from 500 to 3000mm; - wire dimensions: diameter from 5mm to 30mm, for a linear metric weight of wire from 25g to 2500g.

When using vertical axis coils, the following problem frequently arises. The last row of turns runs from bottom to top. The self weight of the spirals not yet unrolled makes them tend to collapse on themselves inside the frame. This can then cause entanglement of the turns, resulting in the blocking of the unwinding facility, or even a breakage of the wire. For coils with horizontal axis, one can witness under the effect of the own weight of the wire and the vibrations due to the unwinding, to a collapse of the turns, with the same risks of entanglement and stop of the supply or rupture some thread. These phenomena can be created or accentuated in particular by shocks or deformations experienced by the coil, during handling, for example, vibrations suffered by the wire during injection, poor horizontal support of the coil (ground and / or pallet The object of the invention is to propose a solution to this problem of regularity of the unwinding of the last layer of turns of the coil of wire, so as to make reliable the operation of the wire distribution installation at the end. winding of a coil and thus ensure the smooth running of the metallurgical treatment under controlled cost conditions. For this purpose, the subject of the invention is an armature for holding a coil of solid or cored wire with an external metal surface for carrying out the addition of substances in a bath of liquid metal by unwinding said coil in said bath , comprising studs enclosing said coil and whose inner faces come into contact with the outermost layer of turns of the wire constituting said coil, characterized in that said inner faces of said uprights comprise, at least over a portion of their length, means tending to intensify the contact between these amounts and the wire by increasing the adhesion between all or part of the turns of the last layer of turns of said wire and the amounts and / or maintenance of all or part of the turns of the last layer of turns of said wire in housings formed on said uprights. Said means can be constituted by a layer of material with a high coefficient of adhesion with metals, such as rubber.

Said means may be constituted by a layer of malleable material deforming in contact with said wire so as to follow the undulations of the outer surface of said turns and thus to define housing for said turns. Said material can be selected from rubber, polystyrene, a synthetic foam, polyurethane. Said means tending to intensify the contact between the uprights and the wire may be formed by undulations formed on the inner walls of the uprights.

Said means tending to intensify the contact between the uprights and the wire may be formed by pins provided on the inner walls of the uprights. Said means tending to intensify the contact between the uprights and the wire may be constituted by a roughness imparted to the inner walls of the uprights. Said roughness can be at least Ra = 2pm and Rm = 4m. As will be understood, the invention consists in providing on the uprights of the armature which traps the coil means tending to intensify the contact between these uprights and the wire, by increasing the adhesion between the wire and the uprights. and / or blocking said wire in housings formed on said uprights, so as to make it more difficult to lower the turns (for coils with a vertical axis) or the collapse of the turns (for the coils with a horizontal axis). This increase in adhesion can be obtained in various ways: by depositing on the surface of the uprights a layer of material increasing the coefficient of adhesion, in other words the friction, between the upright and the wire; depositing on the surface of the uprights a soft coating in which the last layer of wire turns can form housings where the wire is inserted during the caging of the coil; these housings then allow to maintain it in its initial position during the reeling; - By notching notches or pins on the surface of the uprights, wherein the wire is inserted during the caging of the coil; by a simple increase in the roughness of the surfaces of the uprights of the frame which are in contact with the wire. The invention will be better understood on reading the description which follows, given with reference to the following appended figures: FIG. 1 which shows a coil of cored wire trapped in its armature; - Figure 2 which shows schematically in cross section a portion of the last layer of turns of a coil and the amount of a reinforcement according to the prior art in contact with which it is located; - Figure 3 which shows schematically a first example of implementation of the invention; - Figure 4 which shows schematically a second example of implementation of the invention.

FIG. 1 shows a coil 1 of solid or flux-cored wire with a vertical axis whose set of turns is, in addition, kept compact by several substantially longitudinal links surrounding the turns, called circles 2 after removal of the mandrel. The number and nature of these bells may vary depending on the type of wire spool. These rings guarantee the integrity of the coil winding during the phases of handling and transport of the coil. They are intended to be removed after the coil has been placed in its place of use. The wire which composes the coil is wound on a mandrel, during the manufacture of the coil, in several superimposed layers, from the inside to the outside, and each forming a series of turns 3, 4. Note that the part initial 5 of the wire emerges from the central part of the coil 1, so as to allow its connection by mechanical means to the end portion of the wire of another coil. It is thus possible to ensure a continuity of the distribution of the wire when a coil has finished unfolding while the metallurgical treatment of the liquid metal is not completed. As is conventional, the lower face of the spool 1 rests on a pallet 6, from which four vertical uprights 7, generally metallic, surround the spool 1. A winding eye 8, permanently connected to the uprights 7 and enclosing the upper face of the coil 1, preferably completes the armature which maintains the coil 1. The wire passes through the eye 8 which is generally elliptical as shown, but sometimes circular. The eye 8 holds in place all the turns 3, 4 during the injection operations and thus avoids the driving of several turns 3, 4 at a time. The small diameter of the ellipse of the eye 8 corresponds to the diameter of the first internal turn.

In the armatures of the prior art, as shown in Figure 2, there is a direct contact between the inner face 9 of the upright 7 and the last layer 10 of turns 3, 4 of the wire. This inner face 9 of the upright 7 does not have, either, particularities as to the conformation of its surface and / or its surface characteristics, which are simply those of the raw material of manufacture which served to realize it. The consequence is that during unwinding of the last layer 10 of turns 3, 4, which as said, takes place from the bottom to the top of the coil 1, and which drives the wire in the direction materialized by the arrow 11, each turn 3, 4 is subject to: - its own weight P; at the vertical pressure R exerted on it by the turns situated above it, which tends to lower the turns 3, 4 towards the base of the armature; - at the pressure F exerted on it the amount 7; - the adhesion force Al between the amount 7 and the wire. Torsion forces are compensated for by the metal casing of the wire (in the case of a cored wire) and can be generally neglected. Al must be equal in absolute value to P + R for the system to be in equilibrium.

When it comes to a steel-to-steel contact (in the case of a steel reinforcement and a steel-lined cored wire), the coefficient of adhesion is of the order of 0.2, that is that is to say that the force Al resulting from the adhesion between the wire and the upright 7 of the armature is equal to 0.2 x F. This is generally insufficient to avoid the collapse of the turns 3, 4 of the last layer of the reel 1 during reeling. In most cases, this collapse of turns causes their entanglement. The reeling must then be interrupted, thereby causing the cessation of the metallurgical treatment. According to the invention, the internal faces 9 of the uprights 7 of the armature are modified so as to increase very substantially the friction force A2 between the upright 7 and the turns 3, 4 which are in contact with it. In this way, the collapse of the turns 3, 4 of the last layer is braked or even completely prevented during their unwinding. They are thus assured of remaining substantially circular and in contact with the uprights 7, so that their unwinding conditions remain stable and that the incidents that have been mentioned can no longer occur. According to a particular embodiment of the invention, shown in FIG. 3, this modification of the internal faces 9 of the uprights 7 of the reinforcement consists in coating them with a layer 12 of a compound providing a high coefficient of friction with the metal constituting the outer part of the wire, for example a rubber. Under these conditions, for a rubber-to-steel contact, a coefficient of adhesion of about 1 is observed, or even considerably more. This is sufficient to obtain at least a very significant improvement in the behavior of the turns 3, 4 at the end of unwinding, or even the total suppression of the descent of the turns 3, 4, which maintains their relative provisions during the entire unwinding operation. For example, the rubber layer may have a thickness of 0.5mm to 5mm, and the upright 7 may have a width of 10mm to 80mm so that the friction force is exerted on a sufficiently large contact line. Under the same conditions, it is possible to multiply the number of uprights 7 on the circumference of the coil in order to advantageously distribute the force exerted on the turns. By way of example, the number of uprights 7 can be increased from 4 to 6. Another embodiment of the invention, shown in FIG. 4, consists of replacing the relatively thin layer 12 of rubber or other of the variant previous by a thicker layer 13 of a malleable material, ie capable of deforming to match the undulations of the surfaces of the turns 3, 4, so that during the conditioning of the coil in the frame, housing 14 for the turns 3, 4 are formed in said material 13 under the effect of the pressure F exerted by the uprights 7 on the coil 1. This leads to the establishment of an oblique additional force M exerted by the material 13 on each turn 3, 4, and whose vertical component adds to the adhesion force A2 to prevent the descent of the turns 3, 4. This variant of the invention therefore more assured still than the previous to prevent the descent turns 3, 4, in particular by the fact that the coating-wire contact is carried out on larger surfaces than in the case of a non-deformable rubber layer. The material of the malleable layer may, in particular, be a rubber, or a material having mechanical characteristics similar to those of rubber, polystyrene, a synthetic foam, polyurethane or any other material having malleability properties, under the effect the pressure exerted by the wire and the amount 7, able to perform the functions required by the invention. Ideally, this material also has a high coefficient of adhesion with the wire, so that we also find the features of the previous variant. By way of indicative example, it is possible to use for a spool of wire 16mm in diameter, having a metric weight of 605g / m, an inside diameter of 800mm, an outside diameter of 1400mm, a height of 1090mm, confined in a frame made of four U-shaped steel 40x20mm and 5mm thick, an EPDM polymer (ethylene-propylene diene rubber) with an acrylic adhesive on one side and characteristics: - density from 130 to 170 kg / m3 - hardness 38 to 58 Shore 00 - compressive strength (according to the NFR 99 211- 80 50% standard) from 80 to 160 kPa. Another variant of the invention is to provide corrugations or pins on the inner surface 9 of the uprights 7, to give it a configuration defining in advance housing for the turns of the wire, so comparable in principle to that it is found in the variant of Figure 4. This variant is possible in cases where it can ensure excellent regularity of the winding of the wire, so that the turns are always always facing the housing thus formed to enter without difficulty when placing the uprights 7 on the pallet 6. Another variant of the invention consists in simply conferring a high roughness of the order of at least Ra = 2 m and Rm = 4 m to the inner surface 9 amounts 7 by shot blasting or any other comparable method by ensuring to guide the defect profiles to oppose the movement of the turns. This may be sufficient for wire coils of low weight and size. The invention has been described and shown for the case of a coil 1 with a vertical axis during its unwinding. But it goes without saying that it is easily transposable to the case where the coils have their horizontal axis during unwinding.

One of the advantages of the invention is that its implementation does not require any modification to be made to the son known in terms of shapes and / or dimensions.

In the examples described and shown, the wire has a circular section, but the invention can also be adapted to cases where the wire has a section of other shape, for example, hexagonal or octagonal. It should be understood that, at the option of the user, the means tending to intensify the contact between the uprights 7 and the wire may be arranged on the entire surface of the uprights 7, or only over a portion of their length. However, of course, arranging the means tending to intensify the contact between the uprights 7 and the wire over the entire length of the uprights 7 likely to face the coil 1 may make it possible to maintain the turns 3, 4 of the coil 1 at a distance of constant localization during the entire unwinding of the coil 1, which further ensures the success of the operation.

Claims (8)

REVENDICATIONS1. Armature for holding a coil (1) of wire (3, 4) solid or filled with a metal outer surface for carrying out the addition of substances in a bath of liquid metal by unwinding said coil (1) in said bath , comprising uprights (7) enclosing said coil (1) and whose inner faces (9) come into contact with the outermost layer (10) of turns of the wire constituting said coil (1), characterized in that said faces internal members (9) of said uprights (7) comprise, at least over a portion of their length, means tending to intensify the contact between these uprights (7) and the wire by increasing the adhesion between all or part of the turns (3 , 4) of the last layer of turns (10) of said wire and the uprights (7) and / or holding all or part of the turns (3, 4) of the last layer of turns (10) of said wire in formed housings on said uprights (7). 2. Reinforcement according to claim 1, characterized in that said means are constituted by a layer (12) of material with a high coefficient of adhesion with metals, such as rubber. 3. Reinforcement according to claim 1 or 2, characterized in that said means are constituted by a layer (13) of a malleable material deforming in contact with said wire so as to follow the undulations of the outer surface of the turns (3, 4) of said wire and thus to define housing (14) for said turns (3, 4). 4. Reinforcement according to claim 3, characterized in that said material is selected from rubber, polystyrene, a synthetic foam, polyurethane. 5. Armature according to claim 1, characterized in that said means tending to intensify the contact between the uprights (7) and the wire are constituted by undulations formed on the inner walls of the uprights. 6. Reinforcement according to claim 1, characterized in that said means tending to intensify the contact between the uprights (7) and the wire are constituted by pins arranged on the inner walls (9) of the uprights (7). 7. Reinforcement according to claim 1, characterized in that said means tending to intensify the contact between the uprights (7) and the wire are constituted by a high roughness imparted to the inner walls (9) of the uprights (7). 8. Reinforcement according to claim 7, characterized in that said roughness 5 is equal to at least Ra = 2pm and Rm = 4 m.