RU2209841C2 - Metal pouring method - Google Patents

Abstract

FIELD: ferrous metallurgy, in particular, foundry. SUBSTANCE: method involves producing metal melt in intermediate vessel provided with opening, with contour thereof being continuously recovered by adding lump metal; providing bottom discharge of melt into crystallizer with the use of intermediate vessel made in the form of remeltable blank while controlling predetermined volume of produced metal melt. Method is used for pouring any of metals, including high-melting point and reactive metals. EFFECT: wider operational capabilities by providing manufacture of compound articles, including ingots, slabs and shaped blanks. 1 dwg

Description

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

 The closest technical solution is the method of skull melting with bottom discharge of liquid metal into a mold, which includes obtaining a molten metal in an intermediate vessel with an opening, the contour of which is constantly restored by adding bulk metal, and its subsequent bottom discharge into the mold (1).

 The method of skull melting with bottom discharge of liquid metal into the mold allows protecting the melt with the help of a skull from foreign inclusions, and the simplicity of design allows to reduce the cost of the production of ingots. The method includes preparing the melt in an intermediate vessel, melting the bottom of the vessel, and then releasing the melt into the mold. This method is used for the manufacture of ingots.

 The objective of the invention is to increase the efficiency of use and expand technical capabilities by obtaining products of a more complex shape, including ingots, slabs, sheets and shaped blanks.

 The solution of this problem is carried out due to the fact that they use an intermediate tank in the form of a remelted billet and control the set volume of the obtained metal melt.

 The proposed method implements the installation shown in the drawing. The installation includes a melting chamber 1, in which a remelted metal billet 2 is placed, when heated, a melt 3 is formed, merging through the hole 4 into the mold 5. The remelted metal billet 2 can melt under the influence of a remelted electrode 6 (as well as a plasma torch; non-consumable electrode; electronically beam gun, etc.), the melt 3 from which flows down the remelted billet 2.

 Additionally, the melt 3 can be formed from pre-stacked pieces of metal 7 on the workpiece 2. In addition, the metal 7 can be fed during melting to the workpiece 2, until the electrode 6. The internal cavity of the mold 5 can be, for example, in the form of a slab ( as well as a cylinder; a square: a tee, etc.). The mold 5 can be moving for uniform casting of the melt 3 on it, and also be exposed to vibration, shock, etc.

 The remelted billet 2 combines two functions in the technological chain - an intermediate tank and a drain trough, which can significantly simplify the process, reduce the time and energy for moving the melt, its overheating, as well as simplify and reduce the design by reducing the various devices necessary for smelting ingots. In contrast to the prototype, where ingots are manufactured by fusing the entire consumable electrode into a skull, which should be sufficiently capacious, the dimensions of the remelted billet 2 are much smaller, which affects the size of the entire furnace structure.

 In addition, the smelting of a large mass of metal at once in the skull requires a very high accuracy of process control, in contrast to a continuous process, where the role of a regulator can be played by adding one or another amount of bulk metal, and not just power control, as in the first case. Using a moving mold 5 will allow, for example, to produce finished tackle of very small thicknesses at very large lengths, which is very important for sheet rolling production. Gradual adjustment for melting and continuous casting reduces the amount of rejects, since you can always select the required length of a quality ingot from a longer length. With a vertical arrangement of the mold, it becomes possible to produce small section ingots or rods.

 So under the remelted billet it will be possible to install a package of crystallizers of small cross-section, which also reduces the limit and energy consumption during the production of rods.

 The use of bulk metal in the filling reduces the cost of manufacturing the electrodes, it is practically possible to fuse two electrodes, of which one did not go through the pressing process.

 The ability to position the mold 5 as close as possible under the remelted billet 2 (especially in the horizontal position) makes it possible to enhance the heat treatment of the melt discharged from under the arc, and most importantly, the ability to direct the arc to the melt directly in the mold. This eliminates loosening, and rapid cooling in the mold eliminates shrinkage.

Extract from the literature (2):
- "As a result of the analysis of the extensive industrial experience gained in the production of titanium alloy ingots by vacuum arc melting of a consumable electrode in a crystallizer, along with the advantages of this melting method, its significant shortcomings were revealed, p. 7:
- gas saturation;
- enrichment with refractory elements at the bottom of the bath;
- high costs for the production of ingots;
- low yield upon receipt of the semi-finished product;
- the difficulty of obtaining slabs and blanks of small cross section. "p. 8.

 - "The fourth stage is related to the elimination of these drawbacks ... The common thing for this stage is the separation of the melting zone (crucible or intermediate tank) and the ingot formation zone (mold or mold ...", p. 8.

Benefits:
- removal of light and heavy inclusions;
- less need to grind waste;
- high chemical uniformity;
- the possibility of casting into one or more molds with an extract, i.e., obtaining in one remelting ingots-billets of small diameter, flat and hollow ingots.

Disadvantages:
- (with the existing technique for casting metal into a mold), it is necessary to re-melt it to eliminate shrinkage shells and loosening.

Generalization:
“The development of processes combining melting in a skull crucible or an intermediate tank with continuous casting of ingots of given sections should be considered the most promising. For this, it is necessary to solve complex technical problems ...”
- organization of overflow of the melt from the bath into the molds with a given constant speed;
- refining of the melt;
- casting into several molds;
- intensive cooling of ingots;
- Automation and computer control.

 This process was tested at NIIMash in the laboratory of "Pulse Volumetric Stamping" for smelting ingots with a diameter of 60 mm titanium-aluminum intermetallic. Further, these ingots were used for stamping by the method of Impulse Volumetric Stamping of automobile valves. Subsequently, the production of the same automobile valves took place in a combination of the Pulse Volumetric Stamping (IOS) method with a combination of the newly proposed method, i.e., a remelted billet was used with a hole filled with lump metal, and when it was melt by the IOS method, it was hammered directly into the stamp. The first excerpt from the literature (2) explained why the simple and cost-effective prototype was not developed. This is a particular complication of melting control for full fusion of the remelted ingot into the skull and after the melt is drained into the mold. When testing the proposed method, a new method was used to control the melting of the relative heating of the workpiece through the control sensors.

If the heating deviates upward from its control value, the arc power decreases in extreme cases until it is completely turned off, with further melting, in order to avoid early melting. In case of deviation to the smaller side of the same heating from its control value, the power on the arc increases. The computer program is docked with the amount of metal to be melted into the electrode and, on the instructions of the installation operator, it melts precisely the specified volume before releasing it into the mold. In accordance with the generalizing theses of the literature (2), we can say that the present invention provides:
- the organization of the overflow of the melt from the bath into the crystallizers with a given constant speed (since the principle itself does not allow the discharge speed to be different, because either the intermediate tank is completely melted, or there will be no possibility of its melting from the overgrowing of the bath);
- refining of the melt (finding a vacuum pipe for pumping gases in place, near the bath of the melt, contributes to its good refining);
- casting into several molds (the method indicates the profitability and the possibility of such an application);
- intensive cooling of ingots (ingress of the melt into crystallizers of small internal volume contributes to its intensive cooling);
- Automation and control using computers (on the first modification of the installation, a 286 computer was used, modified into a semi-industrial one. A series of experiments on tracking the melt pool showed that the probe should be interrogated for at least 0.01 s for a timely effect on the melting process. That is, without using a computer, the method is simply not feasible).

 All this gives the advantages of this method of casting metal over its prototype (1).

Sources of information
1 Patent 2089633, C 22 V 9/18, 09/10/1997.

 2 Andreev A.L. and others. Melting and casting of titanium alloys. M., Metallurgy, 1994.

Claims (1)

 A metal casting method, including obtaining a molten metal in an intermediate vessel with an opening, the contour of which is constantly restored by adding bulk metal, and its subsequent bottom discharge into the mold, characterized in that an intermediate vessel is used in the form of a remelted billet and the specified volume of the obtained melt is controlled metal.