Venting unit for a Die Casting device

Abstract

The invention relates to a venting unit for a die casting device which has a mold cavity that is adapted to be filled with liquid casting material and a gas suction device that is connected to the mold cavity for extracting gas from the mold cavity by suction, the venting unit comprising a flow labyrinth, the inlet of which is adapted to be connected to the mold cavity and the outlet of which is adapted to be connected to the gas suction device. In order to develop the venting unit in such a way that it makes improved evacuation of the mold cavity possible without the risk that liquid casting material can escape from the venting unit, it is proposed according to the invention that the flow cross-section of the flow labyrinth is variable. Furthermore, a die casting device with a venting unit of this kind is proposed.

Description

[0001]This application is a continuation of international application number PCT / EP2008 / 006180 filed on Jul. 26, 2008 and claims the benefit of German patent application no. 10 2007 054 520.9 filed on Nov. 6, 2007.[0002]The present disclosure relates to the subject matter disclosed in international application number PCT / EP2008 / 006180 of Jul. 26, 2008 and German application number 10 2007 054 520.9 of Nov. 6, 2007, which are incorporated herein by reference in their entirety and for all purposes.BACKGROUND OF THE INVENTION[0003]The invention relates to a venting unit for a die casting device which has a mold cavity that is adapted to be filled with liquid casting material and a gas suction device that is connected to the mold cavity for extracting gas from the mold cavity by suction, the venting unit comprising a flow labyrinth, the inlet of which is adapted to be connected to the mold cavity and the outlet of which is adapted to be connected to the gas suction device.[0004]The inve...

AI Technical Summary

Benefits of technology

[0008]This object is achieved according to the invention in the case of a venting unit of the type mentioned at the beginning by the flow cross-section of the flow labyrinth being variable. This provides the possibility of reducing flow losses within the flow labyrinth when gas is extracted from the mold cavity, since a relatively large flow cross-section can be chosen for the flow labyrinth for the extraction of gas from the mold cavity. The evacuation of the mold cavity can be significantly improved as a result. However, to be able to avoid liquid casting material being able to flow through the flow labyrinth and escape from the venting unit, the flow cross-section of the flow labyrinth can be reduced, so that it is ensured that inflowing casting material reliably solidifies within the flow labyrinth.

[0009]It is of advantage if the flow cross-section of the flow labyrinth is adapted to be varied by liquid casting material flowing into the flow labyrinth. This provides the possibility of choosing the flow cross-section to be comparatively large at the beginning of the casting operation, in order to be able to extract gas effectively from the mold cavity. The extracting operation may continue until casting material filled into the mold cavity enters the flow labyrinth. The inflowing casting material can then bring about the reduction in the flow cross-section of the flow labyrinth, for example by the inflowing casting material impinging with great force on a portion of the wall of the flow labyrinth. The impingement of the portion of the wall with the surge of inflowing casting material can then be used for reducing the flow cross-section.

[0010]It may be provided, for example, that the flow labyrinth has first and second projections, which are opposite to one another and disposed offset in relation to one another in the direction of flow and the spacing between which is variable. The inflowing casting material undergoes a deflection in each case at the first and second projections, a considerable momentum being transferred to the first and / or second projections, so that the projections change their relative position and, as a result, reduce the flow cross-section of the flow labyrinth.

Problems solved by technology

To avoid air bubbles being trapped in the casting material, which is at first liquid and then hardens in a very short time, with the trapped air bubbles possibly impairing the quality of the casting produced, the air can be extracted from the mold cavity by means of a gas suction device.

The narrow gaps impair the extraction capability.

In many cases it has been found that, even though powerful gas suction devices are provided, the mold cavities are only evacuated unsatisfactorily.

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