HU208503B - Method for bottom casting ingots - Google Patents

Abstract

A diagram is given illustrating limitation of hot metal splashing during bottom casting by using a cardboard box placed on the bottom of the ingot mould from where the hot metal is forced to rise into the casting block

Description

Scope of the description: 4 pages (including 1 page figure)

EN 208 503 Β

The present invention relates to a method for casting bottom mold castings, in which molten metal is poured into molds (molds) placed on a casting tray with a pouring tube.

A common method for casting so-called damped, low-oxygen liquid steels in steelworks is the bottom-up, rising casting. In this technological solution, the steel is cast into one or more molds at the same time, so that the liquid metal flows from the steel casting through a closed channel lined with a refractory material. The molds are located on the so-called washer, the bottom is open. The steel beam at the geometric center of the bottom plane of the mold forms at a rate of about 5-7 m / sec, fountain-like from the washer.

This casting system has been used in steel production for decades. For a detailed description of this, see Chapter VII / 1 of the Copper Metallurgy Encyclopedia, and in section 469, section 3.4.4.4, of István Balsay, entitled “Siemens-Martin Steel Production”.

At the start of the casting, the splashing steel beam solidifies on the wall of the mold, its surface is oxidized. The liquid steel rising in the mold does not melt the spattered steel pad as a result of the necessary heat dissipation of the environment, so the oxidized surface adhesion on the surface of the manufactured product causes a flawed material continuity error. This surface defect causes further losses during material processing (depreciation, additional cost of grinding the surface defect, additional blasting costs), or in severe cases the steel product is discarded (loss of scrap).

As a further cost-increasing effect, the problem is that the splashing steel roughly roughens the bottom 1/3 of the wall of the mold (coil) by rough mechanical stress and reduces the life of the mold by about 15-20%.

Therefore, several procedures have been proposed to solve the above problems.

One suggestion is to reduce the flow rate of the flowing melt by increasing the cross-section of the refractory channel. This solution is limited by the resistance of traditionally used refractory materials to increased dynamic erosion heat effects and undesirable swirling during casting due to too fast filling.

Known splashes include the incorporation of a reduced special refractory element into the casting tube to influence the direction of the breaking steel beam. This is an inadequate solution to compensate for a cumbersome, injurious, and subjective - casting mistake occurring at the start of a quick casting, which can also cause a loss.

In addition to the above, other attempts are known, but these are rather complicated and costly, so that the cost of steel production is burdened to such an extent that the product becomes loss-making.

Based on the above, our aim is to provide a solution that allows simple and inexpensive solutions to the problems associated with lower casting, i.e. preventing splashes of molten metal from entering the cocktail and thereby damaging the cocktail and the finished product.

The object is achieved by a method of pouring molten metal into molded castings with a casting tube in a known manner, and where according to the invention, a splash-proof cap of combustible material, preferably hardwood, is placed on the pouring opening of the casting mold and with a clean material for the product to be made, for example, by casting with a casting powder which is otherwise required for casting, which is otherwise required for casting.

The anti-splash cap can be easily produced from the hardwood by folding and firing, preferably in a rectangular shape. The cap (hardwood box) is placed centrally on the molding opening of the molding before the mold is placed on the molding.

In the process according to the invention, the mold thus comprises a cocktail or a cocktail placed on a pad with a pouring tube, wherein the casting pad has a splash-proof cap on combustible material, preferably hardwood.

The anti-splash cap is preferably rectangular and centered on the opening of the casting pad.

The basic advantage of the method according to the invention compared to conventional solutions is that the pouring of liquid metals onto the inner wall of the coil and its stiffening of the finished metal are eliminated and the after-treatment of the finished steel product (grinding, flame blowing) becomes superfluous. Coarse surface scaling resulting from metal casting is also eliminated, which also impairs the quality of the product.

The invention also eliminates the risk of splash damage due to splashes, thus increasing the lifetime of the molds by 15-20%.

The casting powder can be easily placed in the blacksmiths, eliminating the previous, cumbersome and accidental suspension.

In the casting mold, the liquid metal on the casting powder spreads uniformly with the described novel process and, from the first moment, protects the melt surface from the damaging oxidizing effect of ambient air.

A further advantage of the method according to the invention is that it forces the technologically necessary central mold configuration and thus indirectly influences the fabric structure of the molded product.

Further details of the invention are illustrated by way of example in the drawing. It is in the drawing

Figure 1 shows a sectional view of a mold used for the method of the present invention.

It can be seen in the figure that the mold (1) comprises bladders (3) placed on a casting tray (2) with a pouring tube. The central passageway (4) of the (1) tubing (4) is connected to the drainage channels (5) of the casting tray (5) and the

EN 208 503 Β terminates in breakthrough bricks (6) located in the midline of each (3) cocoons.

At the left-hand side of the figure, it can be seen that the molten metal breaking out of the flow brick is deposited on the splash and on the wall of the coil (3). In contrast, on the right side of the coil, it can be seen that, according to the method of the invention, an anti-splash cap (7) ("box") was pressed down with a bag-filled powder.

The anti-splash cap (7) is folded from hardwood with a rectangular shape and is stapled with a stapler.

The method according to the invention can be carried out using the mold shown in the figure as follows:

- After removing the castings of the previous casting, the casting pad is cleaned;

- Place the casting pad on a cooling rack;

- The casting pad cooled down to the required technological temperature is prepared by a conventional casting wall masonry method and placed in the casting (casting), and then fitted with a vertical refractory lining tube for the liquid metal casting channel to the distribution bracket on the casting base;

- Unlike conventional solutions, a cast-in-the-box rectangular-shaped or locally dependent geometric shape is provided on a casting base prepared in the manner described above, on the outlet orifices of the casting channel for conducting the liquid metal;

- We use a bagged powder for technologically necessary bagging to weigh the anti-splash hardwood box (in the case of conventional castings, the bag mold is applied with a braided string);

- The molds (cocoons) at the technological temperature are adjusted to the casting base so that the weighted hardwood box is located in the middle of the bottom plane of the mold;

- The casting system thus prepared is ready for casting liquid metal.

The shape and size of the anti-splash hardwood box used depend only on the cross-section of the mold to be used to reduce the kinetic energy of the metal beam from the casting channel and to provide a smooth, splash-free flow of the liquid metal. The material of the anti-splash box is cardboard-like paper, which is made of pure material from the point of view of the metal product, and its strength is sufficient to withstand the load of the casting powder used for "weighting" (depending on the size of the cast metal product, the weight of the casting powder is 1.0-1.5 kg of casting powder / t specific metal). value). For example, this weight may vary from 6.0 to 9.0 kg for a 6-ton cast steel product. At the given interval, the smallest mass of the powder is sufficient for the application of the invention.

One person can make a splash proof sample by simple folding on a sample, and "mechanized" production is not justified. The patterned, folded paper box is connected to an office stapler at a suitable location and can be used immediately.

The present invention has been used in practice, and direct savings of about one million tonnes of steel products in the casting of alloyed and non-alloyed steels in molds in a year resulted in ten million forints.

Of course, the present invention is not only applicable to steel casting, but also to the casting of a number of other metal or alloy and shaped castings. The shape of the anti-splash cap (box) can also be arbitrary and, if necessary, the weighting can be carried out with any material that is pure in terms of the quality of the molded article.

Claims (6)

PATENT CLAIMS CLAIMS 1. A method for lower casting molds, wherein the molten metal is poured into molds (molds) placed on a casting pad provided with a pouring tube, characterized in that, prior to casting, 2. A process according to claim 1, wherein the weighting is performed with a quantity and quality of casting powder required for casting. The method of claim 2, wherein the casting powder is used in a bag. 4. A method according to any one of claims 1 to 4, characterized in that the splash-proof cap (box) is made of plain cardboard or corrugated paper used for commercial packaging. 5. A method according to any one of claims 1 to 3, characterized in that the splash-proof cap is a rectangular box open on one side and corresponding to the shape of the mold. 6. A method according to any one of claims 1 to 4, characterized in that the splash protection cap is placed centrally, with its open side downward, on the crack opening of the casting pad, prior to applying the mold to the die.