Vaccuum Die-Casting Method

Abstract

The invention relates to an improved vacuum die-casting, in particular for metals and metal alloys which contain Al, Mg, Zn, and Cu. In order to improve the quality of the components, it is proposed to produce vacuum in the mold cavity and the casting chamber cavity in several phases of the die-casting process. The use of the new method is contemplated for both cold-chamber and hot-chamber die-casting.

1 . A method of die-casting of metal, metal alloys, which form a cast mass, under application of vacuum, comprising the steps of:
 a: filling the casting chamber ( 6 ) with the cast mass ( 8 ),   b: sealing a casting chamber cavity ( 5 ) against atmosphere, whereby the steps a and b can be exchanged,   
     characterized in that
 after sealing and separating the casting chamber cavity ( 5 ) from atmosphere, a first vacuum phase is carried out, 
 a second or further vacuum phases are carried out after separation of the casting chamber cavity ( 5 ) from a first conduit to vacuum system ( 12 ). 
 
   
   
       2 . A die-casting method according to  claim 1 , wherein sealing and separation of the casting chamber cavity ( 5 ) from atmosphere takes place by closing the mold ( 21 ). 
   
   
       3 . A method according to  claim 1 , characterized in that sealing and separation of the casting chamber cavity ( 5 ) from atmosphere is carried out by connecting the casting chamber ( 6 ) with the mold. 
   
   
       4 . A method according to  claim 1  characterized in that the sealing and separation of the casting chamber ( 5 ) is carried out by closing a filling opening ( 4 ) with a casting piston ( 3 ). 
   
   
       5 . A method according to  claim 1 , characterized in that separation of the casting chamber cavity ( 5 ) from atmosphere is carried out with a cover closable from outside. 
   
   
       6 . A method according to  claim 5 , characterized in that sealing of the casting chamber cavity ( 5 ) is carried out by a linear movement of a hood ( 7 ). 
   
   
       7 . A method according to  claim 5 , characterized in that sealing of the casting chamber cavity ( 5 ) is carried out by a linear movement of a hood ( 7 ). 
   
   
       8 . A method according to  claim 1 , characterized in that metering of the cast mass ( 8 ) takes place before carrying out the first vacuum phase. 
   
   
       9 . A method according to  claim 1 , characterized in that metering of the cast mass ( 8 ) takes place during or by means of a vacuum phase. 
   
   
       10 . A method according to  claim 1 , characterized in that metering of the cast mass ( 8 ) takes place after carrying out a preceding vacuum phase. 
   
   
       11 . A method according to  claim 1 , characterized in that instead of a vacuum phase, protective or reaction gases are fed into the casting chamber and/or a mold cavity or such a phase is interposed. 
   
   
       12 . A method according to  claim 1 , characterized in that the filling opening ( 4 ) is closed by displacement of the piston. 
   
   
       13 . A method according to  claim 1 , characterized in that separation of the casting chamber cavity ( 5 ) from the first conduit to the vacuum system ( 12 ) is carried out by closing a valve ( 13 ). 
   
   
       14 . A method according to  claim 1 , characterized in that separation of the casting chamber cavity ( 5 ) from the first conduit to the vacuum system ( 12 ) is carried out by displacement of the casting piston ( 3 ). 
   
   
       15 . A method according to  claim 1 , characterized in that vacuum, which remains behind the casting piston ( 3 ) after the first vacuum phase, remains in at least one further phase. 
   
   
       16 . A method according to  claim 1 , characterized in that vacuum, which is necessary for several vacuum phases, is produced with a respective buffer vessel ( 17 ,  18 ). 
   
   
       17 . A method according to  claim 16 , characterized in that the buffer vessels ( 17 ,  18 ) are evacuated by a common arrangement of vacuum pumps ( 19 ). 
   
   
       18 . A hot-chamber die-casting method, wherein a vacuum system is provided with at least two vacuum conduits, including the steps of:
 1. Displacing a casting piston so that a filing opening ( 72 ) is closed   2. Producing vacuum in a casting ladle ( 74 ), an intermediate piece ( 75 ), a mouthpiece ( 76 ) and a mold cavity via a first vacuum conduit ( 12 )
 characterized in that 
   3. a first vacuum phase is carried out after the casting piston passes past the filling opening ( 3 )   4. thereafter, the connection with the first vacuum conduit ( 12 ) is broken   5. finally, a second vacuum phase is carried out.   
   
   
       19 . A hot-chamber die-casting method according to  claim 18 , characterized in that an additional valve ( 77 ) prevents penetration of metal in the first conduit ( 12 ). 
   
   
       20 . A hot-chamber die-casting method according to  claim 19 , characterized in that the additional valve ( 77 ) is provided on the intermediate piece ( 75 ) located between the casting ladder ( 74 ) and the mouthpiece ( 76 ). 
   
   
       21 . A method according to  claim 17 , characterized in that cast mass ( 8 ) contains aluminum as a major component.