Hydraulic casting unit

Abstract

The invention relates to a hydraulic casting unit which is provided for a moulding machine, in particular for a high pressure die casting machine, and which has a casting cylinder with a pressure chamber which acts in the extending direction, a low pressure source, to which the pressure chamber of the casting cylinder is connected fluidically during a preliminary filling phase and / or a mould filling phase, and a high pressure source, to which the pressure chamber of the casting cylinder is connected fluidically during a holding pressure phase. The fluidic connection between the pressure chamber of the casting cylinder and the low pressure source can be opened and closed in a controlled manner by way of a pilot-controlled 2 / 2-way seat valve which has a first connector which is connected tothe low pressure source and a second connector which is connected to that pressure chamber of the casting cylinder which acts in the extending direction. The 2 / 2-way seat valve has a movable main piston with a first control surface, on which the main piston is loaded in the closing direction by the pressure which prevails at a connector, and with a second control surface. Moreover, the 2 / 2-way seat valve has a pilot control valve. The main piston can be loaded in the opening direction on a second control surface by a control pressure which can be switched on by way of the pilot control valve.A hydraulic casting unit is to be designed in such a way that the 2 / 2-way seat valve is flowed through with a very low pressure loss and closes with a low switching time at a time with high repeatingaccuracy in the case of switching of the pilot control valve. This is achieved by virtue of the fact that the main piston is loaded on the first control surface by the low pressure which prevails at the first connector, and that the force which is generated on the second control surface by the control pressure which can be switched on is greater than the force which is generated on the first control surface by the low pressure.

Description

technical field [0001] The invention relates to a hydraulic casting unit which is provided for a forming machine, in particular a die casting machine, and which has a casting cylinder, a low pressure source and a high pressure source, the casting cylinder having a A pressure chamber acting in the direction of extension, the pressure chamber of the casting cylinder being fluidly connected to the low pressure source during the prefilling phase and / or the mold filling phase, the pressure chamber of the casting cylinder being connected to the Fluid connection to the high pressure source described above. The fluid connection between the pressure chamber of the casting cylinder and the low pressure source is opened and closed by a pre-controlled 2 / 2-way central valve having a first port and a second ports, the first port is connected to the low pressure source, and the second port is connected to a pressure chamber of the casting cylinder acting in the extension direction. The 2 / 2...

AI Technical Summary

Problems solved by technology

It has been found that with the known hydrocasting units it is not always possible to ensure a complete reproducibility of the opening and closing times of the 2 / 2-way center valve

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