Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1996-11-21
1998-03-24
Batten, Jr., J. Reed
Metal founding
Process
Shaping liquid metal against a forming surface
164134, 164136, 1641471, 164306, 164337, B22D 1804, B22D 3700
Patent
active
057302030
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to methods for closing the inlet in a mould after non-gravity casting with a non-ferrous alloy of green-sand moulds in a mould-string plant.
BACKGROUND ART
The international patent application WO 93/11892 relates to a method and a casting device for non-gravity casting with a light-metal alloy of green-sand moulds in a mould-string plant like the "Disamatic" moulding plant manufactured and marketed by Baxi Partnership Ltd. of Preston GB. In this known method, depicted in FIGS. 1a-b, the light-metal alloy is pumped by means of an electromagnetic pump from a heated reservoir through a heated ceramic tube into a bottom inlet disposed in the parting surface between the moulds, thus filling the mould. To prevent the metal from flowing out from the mould, the inlet must be closed before the nozzle of the casting device is removed from the inlet, and this specification indicates three different ways of achieving this, viz.:
1) A core provided with a through-going opening is disposed movably parallel to the outer surface of the mould in a guideway in the mould opposite the mould inlet so that the opening in the core during casting of the mould can be brought to lie aligned with said inlet, while the core after full-casting of the mould is displaced so that a compact part of the core is aligned with the inlet and closes it. The specification shows and describes both a horizontally and a vertically displaceable core.
A drawback of this closing method is that during the displacement of the core, the nozzle of the casting device must abut sealingly against the latter with a certain force, thus at least hampering the displacement of the core.
2) After full-casting of the mould, the inlet of the latter is closed by pressing a metal plate obliquely from above down through the mould material encompassing the inlet of the mould, thus closing the inlet. As the pumping direction of the electromagnetic pump is reversed immediately before withdrawing the nozzle of the casting device from its sealing abutment around the inlet opening in the mould, there is a risk that the metal being pumped back carries along with it moulding sand having been torn loose during the pressing-down of the metal plate. During casting of the next mould, this moulding sand will then be pumped into this mould and may cause defects in the casting.
In both above-mentioned methods of closing the inlet of the mould, the nozzle of the casting device is withdrawn from the mould after casting the latter during the stepwise advancement of the mould string, then to be moved forward in abutment against the inlet of the succeeding mould in the mould string for casting said succeeding mould.
3) In this closing method, the nozzle of the casting device is pressed constantly against the side of the mould string, and a cutting edge is disposed at the mould string upstream of the nozzle, said cutting edge "planing" a groove in the side of the mould string, in which groove the nozzle and a chill plate mounted downstream of it are displaced during the stepwise movement of the mould string. During the casting of a mould, the chill plate covers the inlet of the previously filled mould and cools the metal within the inlet to solidification, thus causing the inlet to be closed. This closing method requires rather complicated equipment with means for controlling the force with which the nozzle is pressed against the side of the mould string, as well as the cooling of the chill plate.
SUMMARY OF THE INVENTION
The object of the invention is to provide improved methods of closing the inlet in moulds of the kind described by casting the moulds by means of the known method and with the known casting device and including the object of especially avoiding the drawbacks mentioned under 1) and 2), and to suggest further alternative methods hereof.
A first method of closing the inlet in accordance with the present invention is by using a movable element.
The movable element may be composed of any material capable of resisting the temperature
REFERENCES:
patent: 3903956 (1975-09-01), Pekrol
patent: 4589466 (1986-05-01), Chandley et al.
patent: 4961455 (1990-10-01), Redemske et al.
patent: 5111871 (1992-05-01), Cook
Batten, Jr. J. Reed
Georg Fischer Disa A/S
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