MXPA96002575A - Half and frame to preheat a colada duct from me - Google Patents

Abstract

The present invention relates to a metal pouring duct, it is quickly detachably positioned by means of a frame. The latter consists of a fixed part and a moving part. The duct is of the type comprising a refractory piece, surrounded by an insulating coating, an inductor and a refractory concrete contained in a frame. The preheating means comprises the inductor and an element constituted by a refractory material and an electrical conductor. It is applied to the regular and homogeneous preheating of a metal pouring duct

Description

HALF AND FRAME TO PREHEAT A METAL COLD DUCT DESCRIPTION The present invention relates to the preheating of a metal casting duct. Firstly, a preheating means for a duct, of the type comprising on its length, comprises a hollow refractory piece opening, of cross section surrounded by an insulating coating, which is also surrounded by an inductor surrounded by a contained refractory concrete. in a frame. French patent application No. 93 01 497 in the name of the Applicant, describes a conduit of the type The metal transfer heating ducts are particularly advantageous for the transmission of a metal at the high casting temperature, especially for upward casting under low pressure.When the casting operations have a discontinuous character, the metal The liquid may not be present for a longer or shorter duration in the duct, so it is interesting to keep it, constantly preheated during this time.

^ * ^^ - In the classical technique. the preheating is obtained by means of a graphite susceptor sleeve comprising a straight part and a cocked part that presents some operating drawbacks linked to the complexity of the manufacture of the channel: forming difficulties, trimming difficulties, centering difficulties. These drawbacks increase the manufacturing cost of the conduit. In order to reduce these drawbacks, a liquid metal transmission heating element has been used. This type of closed cross-sectional element rises upwards and opens out on its upper face through a pouring orifice to feed at least one mold of the type comprising over its entire length, at least one heating means constituted by a - » inductor in the form of coil whose cooled coils are ^ traversed by an alternating electrical current. The heating and maintenance of the liquid metal contained in the refractory duct is ensured by the inductor traversed by an alternating current of medium frequency or aita. This heating mode allows transfer directly to the metal, the electric energy in the form of thermal energy. Whether or not it uses an intermediate element such as graphite, the energy transfer is direct and the performance is better. The frequency that runs through the inductor is typically found on the 1000-15000 Hertz scale. An organ of this type no longer ensures by itself, its internal preheating, both before a casting campaign, and between two successive casting operations. In the aforementioned patent application No. 93 01 497, it was planned to perform the preheating by a secondary means such as one that uses gas. However, this preheating means can not be used for long, small diameter conduits, such as a conduit with a length of one meter and a diameter of less than ten centimeters. In addition, heating with gas, in general, is not very precise. The object of the invention is to remedy these drawbacks. For this purpose, the pre-sensing means according to the invention comprises the inductor of the casting conduit and an element constituted by a refractory and electrically conductive material for radiating energy uniformly on the inner surface of the conduit. According to other characteristics: the element constituted by refractory material and electric conductor, is of austenitic metal, which allows to obtain a good energetic yield of the principle until the end of the preheating; - the element of refractory material is nickel alloy containing chromium; - the element of refractory material is graphite; the cross section of the refractory material element is lower and centered relative to the hollow of the refractory piece; - the element of refractory material, is a straight tube or radius of constant curvature. The subject of the invention is also a frame for the quick and detachable installation, in a casting duct, of a refractory material element, of a preheating means in accordance with that described above. This, in order to minimize the thermal loss in the duct between the end of preheating and its filling with metal. To achieve this objective, the frame comprises a fixed part and a moving part on which the element of refractory material is fixed. The fixed part comprises a system for guiding the moving part, in order to keep the refractory element centered on the piece during the entire movement. According to other characteristics: the fixed part comprises diabolic slices to which are associated guide rails belonging to the moving part; - the fixed part comprises at least one fixing means on the frame and centering in relation to the duct; - the centering means comprises a rod that cooperates with a housing provided in the frame. An example of the implementation of the invention will now be described, in relation to the accompanying drawings in which: Figure 1 schematically represents, in vertical section, a frame and a preheating means adapted to a casting duct; Figure 2 schematically represents a side view of the frame and the preheating means; Figure 3 represents the detail of a rail of figure 2 between the diabolic slices. The frame 1 and the preheating means 2 adapted to the pouring duct 3 presented in figure 1, are adapted to the casting under low pressure of metals at high melting points (steels, super-alloys, cast irons). The preheating medium is represented in thick lines in the working position (preheating), and in broken lines in its rest position. The duct 3 is fixed to an oven 4 which may contain liquid metal. The duct 3 is composed of: - a piece in the form of "5" of aluminous ceramic material having an axis 6 of constant radius of curvature R and a circular cross-section; of an insulating covering 7 of fibrous tissue surrounding the piece in the form of "5"; of a helical inductor 8 which is constituted by several turns 9 submerged in a refractory concrete 10 which is contained in a metal frame 11. The inductor is connected to an alternating current generator. A voltage U and a frequency F are applied to its terminals a and b. ** The preheating means 2 is a metal tube of nickel alloy containing 15% chromium. It is centered at the radius of curvature R of the axis of the piece in the form of "5". The frame 1 comprises a fixed, mechano-welded, parallelepiped part 12. The welded-welded elements are assembled vertically and horizontally, to form a squirrel cage. A guide system 13 is integral with the fixed part 12 of the frame. The guidance system is constituted by diabolic slices 14 arranged in threes (14a, 14b, 14c) in the same vertical plane. Two slices 14a, 14c are located inside the circle path C of the preheating element 2. The third slice 14b is located outside the circle path C. Those slices are fixed on a plate 15, which is also fixed mechano-welded element bottom 16 of the part The fixed part 12 of the frame can be lifted and moved by means of a lifting handle 17 fixed on its upper part. On the horizontal lower element 16, a positioning device 18 is fixed on the frame. This device 18 comprises two vertical plates 19 and 20 that extend downwards and that are arranged * • on one side and on the other side of the frame. The horizontal skids 21 and 22 are respectively welded below the plates 19 and 20. The skate 22 is integral with the frustoconical rods 23. The skids 21 and 22 quickly come to rest respectively on bulging horizontals 24 and 25 of the metallic frame 11, located in the upper part of the casting conduit 1. On the plate 25 perforations are provided that open, of vertical axis and that allows the centering of the frame 1 through the intermediary of the rods 23. The frame 1 also comprises a movable part 26 on which the sleeve 27 is fixed which allows the preheating means 2 to be engaged. The preheating means 2 is maintained in the sleeve 27 by means of a screw 28. As shown in Figure 2, the moving part comprises two guide rails 29 and 30 each placed in a vertical plane and centered at the radius of curvature R. The guide rails 29 and 30 are arranged on one side and on the other of the preheating element 2 at a sufficient distance from the pouring duct 3. Each lower end of the rails 29 and 30 comprises a stop stop 31 and 32. Each rail 29 and 30 is guided by a set of three slots 14a, 14b, 14c. The plane of each rail 29 and 30 coincides with the plane of the set of the three slices 14a, 14b, 14c. The rail 29 shown in cross section in figure 3, is guided between the two diabolic slices 14a and 14b, which have a groove 33 in the shape of "V" that allows guiding the rail 29, by centering the edge 34. The rail is maintained by means of a second slit 14b disposed on the opposite side of the cross section of the rail 29.

The invention is not limited in any way to the example described in relation to the appended figures. In a variant, the preheating element 2 can be formed by a small chain constituted by bolts joined together and that can be installed and removed in complex shaped conduits. According to the value of the frequency F, the preheating element 2 can be hollow or full. Indeed, it is more judicious to use a hollow preheating element 2 when the frequency is high (10,000 Hertz) and a preheating element 2 full, when the frequency F is low (1000 Hertz). This heating means according to the invention allows a regular and homogeneous elevation of the temperature at any point inside the duct 3, which avoids, on the one hand, the fissures of the hollow refractory piece 5 at the time of preheating and, on the other hand, part, to set the liquid metal at the moment of its transfer through conduit 3.

Claims (9)

1. NOVELTY OF THE INVENTION Having described the invention, we consider it as a novelty, and therefore, we claim as our property, what is contained in the following clauses. 1. Means for preheating a metal casting duct of the type comprising on its length, a hollow refractory piece opening, of closed cross section, successively surrounded by: - an eventual insulating coating; - an inductor; a refractory concrete contained in a framework; characterized in that it comprises the inductor and an element constituted by a refractory material and electric conductor to radiate the energy in a uniform manner on the inner surface of the conduit; the cross section of that refractory element is lower and centered in relation to the recess of the refractory piece.
2. 2. Preheating means according to the preceding clause, characterized in that the element constituted by refractory material and electric conductor, is made of austenitic metal.
3. 3. Preheating means according to clauses 1 or 2, characterized in that said refractory element is made of nickel alloy containing chromium.
4. 4. Preheating means according to clause 1, characterized in that the aforementioned element of refractory material is graphite.
5. 5. Preheating means according to any of the preceding clauses, characterized in that the element of refractory material, is a straight tube or radius of constant curvature. /
6. 6.- Rack for the rapid and removable placement in a casting duct, of an element of material refractory to a medium, of preheating according to any of the preceding clauses, characterized in that it comprises a fixed part and a moving part on which the element of refractory material is fixed; the fixed part comprises a system for guiding the moving part, so as to keep the refractory element centered on the part during the entire movement.
7. 7. Casting according to the preceding clause, characterized in that the fixed part comprises slices to which guide rails belonging to the moving part are associated.
8. 8.- Frame according to any of clauses 6 or 7, characterized in that the fixed part comprises at least one fixing means on the frame and centered in relation to the conduit.
9. 9.- Frame according to the preceding clause, characterized in that the centering means comprises a rod that cooperates with a housing provided in the frame. ¥