Die-casting machine having a shut-off valve in the melt inlet channel and operating method

Abstract

A die-casting machine has a casting mould, a casting chamber, a casting piston, a melt inlet channel, a shut-off valve in the melt inlet channel, a melt outlet channel, and a control unit for controlling the casting piston. For carrying out a respective casting process, the die-casting machine is configured, for a mould-filling phase, to bring the shut-off valve into a closed position, and to control the casting piston to advance from a casting start position to a filling end position, in order to press melt material into the casting mould via the melt outlet channel, and, for a subsequent refilling phase, to bring the shut-off valve into an open position and to control the casting piston to move back to the casting start position, in order to supply the casting chamber with melt material via the melt inlet channel. The machine is configured to keep a closure nozzle in the melt outlet channel closed in the refilling phase and, in the mould-filling phase, with the shut-off valve remaining closed, to firstly move the casting piston back from the casting start position to an additional stroke position and to subsequently advance it from the additional stroke position via the casting start position to the filling end position, and at this time to keep the closure nozzle closed during the return movement of the casting piston to the additional stroke position and to only open it when the casting piston advances again.

What is claimed is: 
     
         1 . A die-casting machine, comprising:
 a casting mould;   a casting chamber;   a casting piston arranged in an axially moveable manner in the casting chamber;   a melt inlet channel which leads into the casting chamber;   a shut-off valve in the melt inlet channel;   a melt outlet channel which leads from the casting chamber to the casting mould; and   a control unit for controlling the casting piston; and   a closure nozzle provided in the melt outlet channel, wherein   for carrying out a respective casting process, the control unit and the shut-off valve are configured, for a mould-filling phase, to bring the shut-off valve into a closed position, and to control the casting piston in the casting chamber to advance from a casting start position to a filling end position, in order to press melt material into the casting mould via the melt outlet channel, and, for a subsequent refilling phase, to bring the shut-off valve into an open position and to control the casting piston to move back to the casting start position, in order to supply the casting chamber with melt material via the melt inlet channel, and   the control unit, the shut-off valve and the closure nozzle are further configured to keep the closure nozzle closed in the refilling phase and, in the mould-filling phase, with the shut-off valve remaining closed, to firstly move the casting piston back from the casting start position to an additional stroke position and to subsequently advance it from the additional stroke position via the casting start position to the filling end position, and at this time to keep the closure nozzle closed during the return movement of the casting piston to the additional stroke position and to only open it when the casting piston advances again.   
     
     
         2 . The die-casting machine according to  claim 1 , wherein
 the closure nozzle has a melt-plug-forming nozzle part and/or a nozzle part which can be varied in a controllable manner in terms of its passage cross section.   
     
     
         3 . The die-casting machine according to  claim 1 , wherein
 the shut-off valve is in the form of a shut-off control valve which is controllable by the control unit or is in the form of a non-return valve which is preloaded in its closed position.   
     
     
         4 . The die-casting machine according to  claim 3 , further comprising:
 a valve actuator, activated by the control unit, for actuating the shut-off control valve.   
     
     
         5 . The die-casting machine according to  claim 1 , further comprising:
 a valve sensor unit for sensing one or more measured variables of the shut-off valve and/or of the closure nozzle.