RU2517066C2 - Method and device for production of high-quality metal - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Disc blank is placed on the mould to fuse it by inductor at retaining the blank side surface in suspended state. Mould top part is shaped to truncated cone while mould bottom features the same cone but continued to geometrical cone vertex. Conical insert made from pre-purified metal is fitted in cavity between said disc and said mould to close the mould inlet. Blank is fused from periphery to form the conical front. All light inclusions are displaced to cone vertex while heavy inclusions are collected at cone bottom to get frozen in wall accretion. At bottom drain, pure melt only flows in the mould while dirty melt stays on the mould which is detached after production of the ingot.

EFFECT: higher quality of metal owing to deep refining.

3 cl, 7 dwg

Description

The proposed group of inventions relates to the field of foundry and can be used for casting any metals, including refractory and chemically active.

As an analogue of the invention, patent [1] is adopted (RU 2286398 C2, C22B 9/20, 09/27/2003), where the melt is produced in a melted billet with subsequent exposure to high pressure to move it to a stamp located at a certain distance below workpieces, while the stamp is moved to meet the falling melt before impacting the workpiece. This analogue allows you to process any metals, including refractory and chemically active.

The closest technical solution, as a prototype, is a method of Disk bottom discharge [2] (RU 2353472 C2, B22D 39/00, 07/01/2004), which includes the production of a melt in a melted disk billet. The moment of penetration is fixed, which allows exposure to the melt of gas pressure to form a flat front of the melt, the workpiece is moved inside the inductor as it melts. This method provides a high density of the ingot, a fine-grained structure and a uniform chemical composition.

The objective of the invention is to increase the efficiency of use and expand technical capabilities, by improving the quality of the metal with its deeper refining.

The problem is achieved in that the method of casting metals involves installing a disk billet on a mold, melting the disk billet with an inductor while holding the molten side surface of the disk billet in suspension due to the electromagnetic field, and the bottom discharge of the melt into the mold after melting the billet, while the bottom of the billet is positioned higher the lower end of the inductor, the form is performed in the upper part in the form of a cone with a truncated top, and the bottom of the workpiece is made conical and corresponding to the cone of the form, a conical insert made of purified metal is installed in the cavity formed between the preform and the mold, and the mold is closed by the insert, and the preform is melted from the periphery with the formation of a conical melting front and the light inclusions are forced out to the top of the conical melting front, and heavy inclusions are to the base and periphery of the conical melting front, after the bottom discharge of the purified melt into the mold and receipt of the ingot, the upper part of the ingot with inclusions is cut off.

SUBSTANCE: metal casting device comprises a melting chamber with a melted disk billet, a mold, an inductor located in the central part of the melting chamber, capable of holding the molten side surface of the billet in suspension, while the upper part of the mold is made in the form of a truncated cone on which the disk billet is mounted , while the bottom of the workpiece is made in the form of a cone corresponding to the cone of the upper part of the mold, continuing to the top of the geometric cone and forming a cavity in which placed conical insert made of previously purified metal. The upper part of the form is made in the form of a separate ring, below which is the remaining part of the form. This allows the impurities to leave on the ring, and the ingot to form in the lower part of the form.

The proposed method implements the installation shown in figure 1. The installation includes a melting chamber 1, in which a cooled inductor 2 is placed, in which the melt disc 3 is stationary mounted, so that when it is melted, the melt located on the side is kept in suspension and cannot merge to the side. To do this, the lower end of the disk 3 is installed above the lower end of the inductor 2, by the value N. The inductor can be single-turn or multi-turn, as well as with separate power supply of the turns. Disk 3 is mounted directly on form 4 with a central sprue hole. The disk 3 is mounted on the form 4 in such a way that its end lower part rests on the end upper part of the form, and the side part is open and not screened by the form. Figure 1 shows that the form 4 can be made of copper with cooled channels 5, which allows to obtain highly pure metals and produce ingots with a fine-grained structure. The bottom is closed by the pan 6, the sealing is provided through the seals 7. The housing 1 and the form 4 are sealed through the seal 8. The disk 3 is melted from the side and from the top, with the formation of a conical melting front directed upward. Melting of the disk 3 occurs until the melt reaches the lower part of the preform, after which the melt is drained into mold 4, a small part of the disk 3 remains in the form of a cone or ring on mold 4. Due to the hydrodynamic features of light inclusions, the melt is cleaned, since these inclusions float to the surface of the melt and accumulate at the center of the mirror bath melt. Therefore, after the melt is drained into the mold, they remain on the surface of the ingot. In order to remove inclusions, the upper part of the ingot is cut off. According to the same principle, heavy inclusions accumulate at the bottom at the periphery of the disk, where they freeze into the skull, as the periphery is cooled by shape. Therefore, heavy inclusions also remain in the upper part of the ingot, at the location of the disk. To remove them from the ingot, this part is cut off.

In order to completely eliminate the ingress of light and heavy impurities into the mold, the upper part of this mold, which the disk comes into contact with, is made in the form of a cone with the tip pointing up. In this case, the cone is truncated, due to the fact that it intersects the internal cavity of the form. But the bottom of the disk itself is made in the form of the same cone, which copies the configuration of the shape cone, with the only difference being that it is not a truncated cone. A cone 9 is shown in the cavity formed between the disk and the mold, as shown in FIG. 1, made of previously purified metal. This cone blocks access to the refining melt formed from the metal of the disk, giving it time to clear itself of heavy and light impurities before it enters the mold.

More fully, the metal cleaning process is shown in FIGS. 2, 3, 4, 5, 6. FIG. 2 shows a disk 3 with a cone 9 that is mounted on the mold 4. The cone 9 overlaps the internal cavity of the mold 4, where the cleaned metal will merge. Figure 3 shows the lines of force 10 of the electromagnetic field, under the action of which the metal in the disk begins to melt. A feature of this melting is that the lines of force especially tightly enclose the disk along its periphery. Each frequency of the electromagnetic field has a certain depth of penetration into various metals, so the melt begins to form at first only along the side surface of the disk. In this case, the feature is that the lower part of the melt ring, supported by a copper cooled mold, solidifies, and the upper one heats up more and more. The electromagnetic lines above the upper end of the disk are not dense, which means that not so high heating occurs from the upper part of the disk as from the side. Due to these features, the resulting molten metal on the disk begins to take the form of a ring, expanding all the way to the top. Under the pressure of the electromagnetic field, which prevents gravity and keeps the melt from draining in addition to the shape, the melt at some point is squeezed out by this field onto the end of the disk.

After that, the melting of the metal occurs mainly under the influence of direct heating of the metal on the side surface and heating of the metal located on top, which, under the influence of convection, transfers its heat to the still molten metal located on top of the disk. Thus, figure 3 shows the melting point, where the melt forms a kind of cap that covers the solid phase of the metal, which takes the form of a cone, the tip pointing up.

As you know, the electromagnetic field due to changes in its frequency, differently affects various metals and non-metals. So, for example, by changing the frequency in a narrow range on induction furnaces, it is possible to achieve heating of various metals in different ways. At one frequency and the same power, at the same time it will melt faster, for example titanium, and at a different frequency - iron. The farther the remelted substances are in their physical properties, the greater the frequency range that separates them. The harmful inclusions present in the metal are various compounds of oxygen, carbon, nitrogen, hydrogen, etc. compounds with a remelted metal, as well as particles of foreign metals coming from the ligature into the base metal. For iron and titanium, for example, particles of tungsten, molybdenum, niobium, etc. can serve as heavy inclusions. If it enters the main ingot after melting, both heavy and light inclusions are harmful impurities, since when processed by pressure of this ingot, they are stress concentrators, from which a crack begins to develop and destroy the base metal. This negative effect is especially manifested when thin wire, thin-walled pipes, sheets are rolled, where rupture, delamination, or crack can occur upon inclusion — all this leads to the rejection of expensive, final products. It is especially dangerous when these inclusions remain undetected in the finished product, bearing high loads during operation, under the influence of which, after a time, the part breaks. Particular danger manifests itself in such details as aircraft turbine blades.

In continuation of the description of the metal cleaning process, in Fig. 3, light inclusions 11 having a lower density and not heating up so intensely, under the influence of the electromagnetic field frequency tuned to the molten base metal, begin to rise up to the very top, where they accumulate along the axis of the disk. In this place, the metal that receives the least heat from the electromagnetic field and gives off heat due to convention to the lower layers of the molten metal has an increased viscosity. This is an additional factor contributing to the retention of light inclusions on the surface, allowing them to remain there until the end of melting and not actively dissolve in the bulk of the melt.

Heavy impurities 12 (figure 3), having a higher density than the base metal, moving in the melt, gradually begin to slide down an inclined surface formed by a solid phase cone. At the foot of this cone, they begin to freeze into the skull, no longer involved in the main melt.

Figure 4 shows that the cone becomes more gentle, but the position of the light inclusions 11 and heavy impurities 12 remains the same. Figure 5 shows that the top of the cone, installed from previously cleaned metal, is molten, while the main metal of the disk is also almost molten, a small part of it in contact with the form does not participate in further melting, as it turns into a skull. Figure 6 shows that the purified melt enters the mold, the internal cavity of which is smaller in volume than the volume of the entire metal. For example, 80% of the total metal can merge into a mold, and 20% of the metal can remain on the mold, in which there are light inclusions 11 and heavy impurities 12. Then this part is cut off and can go to re-melt or deform. In order not to produce a piece of the ingot, the disk is mounted on a separate support, and the mold is located at a certain distance below, when the melt is drained, part of it with impurities remains on the support, and the other merges into the mold, separating from the contaminated part.

Figure 7 shows the installation, where a disk 3 is mounted in the chamber 1 with the inductor 2, with a cone 9 of previously purified metal, which is located on the cooled ring 13, made in the form of a solid ring or a ring consisting of separate sectors. Along the axis of the ring 13 is a mold 14 mounted on the lower case 15, which is sealed with the chamber 1 through the seal 8. In this case, the disk is melted using adjustable power on the inductor, so that part of the disk with light and heavy remains on the ring 13 inclusions. The adjustment is carried out due to the fact that the power at the inductor is set depending on the mass of the metal that it melts, as soon as the melt drains into the mold, the mass of the metal in the inductor begins to decrease, and with it the power at the inductor starts to decrease proportionally. The impurities that are concentrated in the disk during the melt discharge, having a higher melting point, bind a part of the melt remaining inside the inductor, at which power is simultaneously reduced, so a part of the metal remains on the support ring 13, and the other part of the melt, purified from impurities, merges into form 14, where the workpiece or ingot is produced.

This method and device allows very efficient to obtain high-quality molten metal and guaranteed to clean it of heavy and light impurities. This invention is especially effective for use in aviation and space topics, where special attention is paid to the quality of the metal. The installation created for its implementation is very compact, due to which its distribution will not be associated with high costs.

In this regard, the present invention can be considered useful and effective for use in production, reducing the cost of equipment and manufactured products, while allowing to obtain products with high quality metal.

Unlike the analogue and prototype, the present invention provides:

- receiving high quality products;

- compact device and high energy savings;

- automatic organization of the drain of the melt from the smelted billet into molds, molds, etc .;

- intensive cooling of the melt during its crystallization;

- reliable automation and process control.

Therefore, the present invention is expediently considered useful for use in industry, upon receipt of complex high-quality products from titanium, niobium, zirconium, steel, aluminum, magnesium, etc. metals.

LITERATURE

[one]. A.E. Volkov - RU 2286398 C2, C22B 9/20, 09.27.2003.

[2]. A.E. Volkov - RU 2353472 C2, B22D 39/00, July 1, 2004.

Claims (3)

1. The method of casting metals, including installing the disk billet on the mold, melting the disk billet with an inductor while holding the molten side surface of the disk billet in suspension due to the electromagnetic field, the bottom drain of the melt into the mold after the billet is melted, with the bottom of the billet being placed above the lower end of the inductor , the shape is performed in the upper part in the form of a cone with a truncated apex, and the bottom of the workpiece is made conical and corresponding to the shape cone, into the cavity formed between the with a shape and shape, a conical insert made of purified metal is installed and the input is closed by the insert, and the workpiece is melted from the periphery with the formation of a conical melting front and the light inclusions are forced out to the top of the conical melting front, and heavy inclusions to the base and periphery of the conical front melting, moreover, after the bottom discharge of the purified melt into the mold and receipt of the ingot, the upper part of the ingot with inclusions is separated. 2. A device for casting metals containing a melting chamber with a melted disk billet, a mold, an inductor located in the central part of the melting chamber, capable of holding the molten side surface of the billet in suspension, characterized in that the upper part of the mold is made in the form of a truncated cone, which the disk blank is installed, while the bottom of the blank is made in the form of a cone corresponding to the cone of the upper part of the mold, continuing to the top of the geometric cone and forming a cavity in which a conical insert made of previously purified metal is placed. 3. The device according to claim 2, characterized in that the upper part of the mold is made in the form of a separate ring.

Images