DEVICE AND METHOD FOR LOW-PRESSURE CASTING OF METAL MELTS

Abstract

A device and a method for the low-pressure casting of metal melts, comprising a casting furnace (1), a feed channel (2) for the metal melt, a channel (4) in the direction toward the casting mold (5), and a feed (6) for the gaseous pressure application, an intermediate container (7) being disposed between the casting mold (5) and the channel (4), and an access (8) for adding an inoculating agent (9) being provided in the intermediate container (7).

Description

BACKGROUND OF THE INVENTION

The invention relates to a device for the low-pressure casting of metal melts, comprising a casting furnace, a feed duct for the melt, a duct in the direction toward the casting mold and a feed for gaseous pressure application.

During low-pressure casting, the melt is conveyed via a riser into a casting cavity, counter to the force of gravity, by subjecting the metallic melt to gaseous pressure application in a furnace.

During gravity casting, melts which have additives or inoculants added to them before the casting for reasons of nucleation are treated before they enter the mold in the casting stream, in the tundish and/or in the mold itself.

According to the prior art, lumps of inoculant can be introduced, during the low-pressure casting, in the region of the mold runner in order to dissolve as the mold is filled. The disadvantage frequently associated with this is, in particular, that the inoculant in the metal melt is not distributed in a satisfactory manner in the casting mold. Different concentrations of the inoculant in the melt can result in considerable deviations in the desired properties of the cast pieces. This known technique requires careful adjustment of the composition and of the solution behavior of the inoculant.

In order to minimize these disadvantages, it is an object of the invention to use a device and a process for low-pressure casting in such a way that the melt is already present with a uniformly distributed quantity of inoculant in an intermediate vessel, before the actual filling of the mold.

SUMMARY OF THE INVENTION

According to the invention, the object is achieved by virtue of the fact that an intermediate vessel is arranged between the casting mold and the duct, an access point being provided in the intermediate vessel for the addition of an inoculant.

The option of a separate access point for the addition of an inoculant to an intermediate vessel between the casting furnace and the casting mold makes it possible to feed a precisely set quantity of inoculant at the desired point in time in a simple manner.

According to a preferred embodiment, an overflow wall is arranged inside the intermediate vessel. It has advantageously been shown that optimum distribution of the inoculant in the melt, in particular by the flow, is achieved when the inoculant is introduced upstream of the intermediate wall.

Further possible embodiments are described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment is shown in the drawing.

FIG. 1 shows a sectional view of a furnace.

DETAILED DESCRIPTION

The casting furnace 1 comprises a feed duct 2 for the filling operation with metal melt 3. The feed duct 2 can be closed by means of a cover 14. A feed 6 is provided on the casting furnace 1 in order to apply gas pressure to the melt. Furthermore, a duct 4 adjoined directly by the intermediate vessel 7 is fitted on the casting furnace 1. The casting mold 5 is arranged above the intermediate vessel 7 and is connected to the intermediate vessel 7 by way of the riser 13 via the opening 11. A tubular attachment 15 for the addition of the inoculant 9 is fitted at the access point 8 to the intermediate vessel 7. An overflow wall 10 for the melt 3 is provided inside the intermediate vessel 7 and is arranged slightly downstream of the end of the duct 4.

The casting operation proceeds as follows:

First of all, the casting furnace 1 is filled with metal melt 3 via the feed duct 2. After the casting furnace 1 has been filled, the feed duct 2 is closed in a gas-tight manner by means of a cover 14. The pressures p1, p2 and p3 correspond to atmospheric pressure. For the transport of iron into the intermediate vessel, the chamber 16 is subjected to the application of pressure with a gaseous medium. The pressure p1 is greater than the pressures p2 and p3. The melt begins to flow into the intermediate vessel 7 via the duct 4 and the overflow wall 10. At the same time, the inoculant 9 is added via the tubular attachment 15. In FIG. 1, the addition opening is arranged between the overflow wall 10 and the casting mold 5. It is likewise conceivable to add the inoculant 9 in the region 17, i.e. upstream of the overflow wall 10. The inoculant 9 is mixed homogeneously with the metal melt 3 owing to the flow of the metal melt 3. In order to fill the casting mold 5, it is necessary to build up the pressure p2, which corresponds to the height ΔH.

After the mold has been filled, p2 is lowered to such an extent that the melt located outside the casting mold can flow back into the intermediate vessel 7.

Claims

1-6. (canceled)

7. An apparatus for the low pressure casting of metal melts, comprising:

a casting furnace having an inlet feed duct, an outlet duct and a feed for gaseous pressure application;

a casting mold downstream of the outlet duct;

an intermediate vessel located between the outlet duct and the casting mold; and

an access point to the intermediate vessel for the addition of an inoculant to the metal melt in the intermediate vessel.

8. The apparatus according to claim 7, further including an overflow wall arranged in the intermediate vessel.

9. The apparatus according to claim 8, wherein the access point for the inoculant is arranged upstream of the overflow wall.

10. The apparatus according to claim 7, wherein the intermediate vessel has an opening and a riser is arranged inside the intermediate vessel at the opening and the casting mold is connected directly to the riser above the opening.

11. A process for the low pressure casting of metal melts, comprising:

providing a casting furnace having an inlet feed duct, an outlet duct and a feed for gaseous pressure application;

providing a casting mold downstream of the outlet duct;

providing an intermediate vessel located between the outlet duct and the casting mold;

providing an access point to the intermediate vessel for the addition of an inoculant to the metal melt in the intermediate vessel; and

introducing an inoculant into the metal melt in the intermediate vessel through the access point.

12. The process as claimed in claim 11, including adding the inoculant in the form of granules.