Process and apparatus for casting titanium aluminide components

Abstract

A process for casting TiAl components, having the following process steps: producing a melt (S) of the TiAl material below an inert gas fill (IF); placing a casting mold (1) on a gate (2) in a gastight manner; flooding the casting mold (1) with inert gas (IG) by opening a closure mechanism (7) which is arranged at the gate (2) and is connected to an inert gas source (8); pressing the melt (S) through the gate (2) into the casting mold (1) by increasing the pressure (P) of the inert gas fill (IF) above the melt (S) while at the same time evacuating the inert gas (IG) from the casting mold (1), and stopping the inflow of inert gas (IG) as soon as it is determined that the melt (S) passes above the position of the closure mechanism (7).

Claims

1. A process for casting TiAl components, comprising the following process steps: producing a melt (S) of a TiAl material below an inert gas fill (IF); placing a casting mold (1) on a gate (2) in a gastight manner; flooding the casting mold (1) with inert gas (IG) by opening a closure mechanism (7) which is arranged at the gate (2) and is connected to an inert gas source (8); pressing the melt (S) through the gate (2) into the casting mold (1) by increasing the pressure (P) of the inert gas fill (IF) above the melt (S) while at the same time evacuating the inert gas (IG) from the casting mold (1), and stopping the inflow of inert gas (IG) as soon as it is determined that the melt (S) passes above the position of the closure mechanism (7).

2. The process as claimed in claim 1, comprising reducing the pressure (P) of the inert gas fill (IF) as soon as the casting mold (2) has been filled, and restarting the supply of inert gas (IG) to the closure mechanism (7) until the fill level of the melt (S) has reached below the closure mechanism (7).

3. The process as claimed in claim 2, wherein filling of the casting mold (2) is detected through a discharge of melt (S) at an evacuation opening (10) of the casting mold (2).

4. The process as claimed in claim 3, wherein the filling of the casting mold is detected optically.

5. The process as claimed in claim 2, further comprising closing the closure mechanism (7) while maintaining the supply of inert gas (IG) to the melt (S) below the gate (2).

6. The process as claimed in claim 1, wherein the melt (S) is supplied proceeding from a melting crucible (5), provided with the inert gas fill (IF), via a riser (4) to the closure mechanism (7) and the gate (2).

7. The process as claimed in claim 1, wherein the inert gas (IG) is supplied from a vessel (8) as an inert gas source to the closure mechanism (7) via a connection line (11).

8. The process as claimed in claim 1, wherein the closure mechanism (7) is controlled via a system monitoring device (9).

9. An apparatus (12) for casting TiAl components, comprising a melting crucible (5); a riser (4), which connects the melting crucible (5) to a gate (2); and a casting mold (1) which can be placed on the top of the gate (2), wherein an openable and closable closure mechanism (7) is arranged at the gate (2), and wherein the closure mechanism (7) is fluidically connected to an inert gas source (8) via a connection line (11).

10. The apparatus as claimed in claim 9, wherein the closure mechanism (7) is connected to a system monitoring device (9) for signaling purposes.

11. The apparatus as claimed in claim 9, wherein the inert gas source (8) is a vessel.

12. The apparatus as claimed in claim 9, wherein provision is made of an optical detection device (12), which monitors an evacuation opening (10) of the casting mold (1).

13. The apparatus as claimed in claim 9, wherein the casting mold (1) is arranged in an exchangeable molding box (6).

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further details, advantages and features of the present invention become apparent from the following description of an exemplary embodiment with reference to the drawing, in which:

(2) The single FIGURE of the drawing shows a schematically greatly simplified basic illustration of an apparatus 12 according to the invention for casting TiAl components, which is suitable for carrying out the process according to the invention as mentioned in the introduction.

DETAILED DESCRIPTION OF THE INVENTION

(3) The apparatus 12 has a casting mold 1, which, in the particularly preferred embodiment shown in the FIGURE, is arranged in a molding box 6 of exchangeable configuration. In the FIGURE, the double-arrows V denote the feed direction of these molding boxes 6, where a further molding box 6′ with a casting mold 1′, which has already been filled and accordingly has been advanced in the feed direction V, is arranged to the left alongside the molding box 6 or the casting mold 1 shown in the FIGURE.

(4) In the filling position shown in the FIGURE, the casting mold 1 is placed onto a gate 2 from above in a gastight manner. The gate 2 in turn is provided with a closure mechanism 7, which is controlled by a system monitoring device 9.

(5) The apparatus 12 furthermore has a melting crucible 5, in which the melt S of the TiAl material is produced, the melt S being produced under an inert gas fill IF which is at a pressure P.

(6) The melting crucible 5 is connected to the gate 2 and to the closure mechanism 7 arranged thereon via a riser 4. The closure mechanism 7 is moreover connected via a connection line 11 to an inert gas source or an inert gas vessel 8, from which inert gas IG, which can likewise be kept at an adjustable pressure, is supplied.

(7) The FIGURE shows a state in which the melt S has not yet reached the closure mechanism 7 and the gate 2, and therefore, to avoid contact with air, the melt S is also covered in the riser 4 with inert gas IG, which is also conducted into the casting mold 1 via the closure mechanism 7. The closure mechanism 7 is preferably connected to a system monitoring device 9 for signaling purposes.

(8) To introduce the melt S into the casting mold 1, the pressure P of the inert gas fill IF is increased, such that the melt S passes via the riser 4, the closure mechanism 7 and the gate 2 into the casting mold 7, until the latter has been filled completely, this preferably being determined by an optical detection device 12 on the basis of the discharge of melt from an evacuation opening 10 of the casting mold 1.

(9) The melt S is preferably supplied proceeding from a melting crucible 5, provided with the inert gas fill IF, via a riser 4 to the closure mechanism 7 and the gate 2. The inert gas IG is preferably supplied from a vessel 8 as an inert gas source to the closure mechanism 7 via a connection line 11.

(10) Preferably, the pressure P of the inert gas fill IF is reduced as soon as the casting mold 2 has been filled, with restarting the supply of inert gas IG to the closure mechanism 7 until the fill level of the melt S has reached below the closure mechanism 7. When the filling of the casting mold 2 is detected through a discharge of melt S at an evacuation opening 10 of the casting mold 2, this is preferably detected optically. The process preferably further comprises closing the closure mechanism 7 while maintaining the supply of inert gas IG to the melt S below the gate 2.

(11) It is to be added that a suitable seal 3 is provided at the gate 2 so that the casting mold 1 can be placed on the gate 2 in a gastight manner.

(12) In addition to the above written description of the invention, reference is hereby explicitly made, for additional disclosure thereof, to the diagrammatic illustration thereof in the single FIGURE of the drawing.

LIST OF REFERENCE SIGNS

(13) 1 Casting mold 2 Gate 3 Seal 4 Riser 5 Melting crucible 6, 6′ Molding box 7 Closure mechanism 8 Inert gas source/Inert gas vessel 9 System monitoring device 10, 10′ Evacuation opening 11 Connection line 12, 12′ Optical detection device V Feed direction IF Inert gas fill above the melt S IG Inert gas in the riser 4 P Pressure of the inert gas fill IF